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A first-class lever has the fulcrum located:
- At one end with the load at the other
- Between the effort (force applied) and the load (resistance) ✓
- Between the load and the end of the lever
- Not at all — first-class levers have no fulcrum
Three classes of levers, distinguished by the positions of fulcrum, effort, and load: (1) FIRST-CLASS: fulcrum is BETWEEN effort and load. Examples: seesaw, scissors, crowbar, pliers, claw hammer pulling nails. Effort and load move in opposite directions. Mechanical advantage can be >1, =1, or <1 de…
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A fixed (single) pulley provides what mechanical advantage?
- 2
- 1 — it changes the direction of force but does not multiply it ✓
- 4
- 0
Pulley mechanical advantage equals the number of rope segments supporting the load. (1) FIXED PULLEY (single, attached to a fixed point): MA = 1. It changes direction (pulling down to lift up) but does not reduce the force needed. The load and effort move equal distances. Example: a flag-raising pul…
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If gear A has 20 teeth and meshes with gear B that has 60 teeth, when gear A makes 6 full rotations, how many rotations does gear B make?
Gear ratio = (teeth of driven gear) / (teeth of driver gear) = 60/20 = 3:1. When a smaller gear drives a larger gear, the larger gear rotates SLOWER but with more torque. Calculation: gear A (20 teeth, 6 rotations) — total teeth moved = 20 × 6 = 120 teeth. Gear B has 60 teeth, so 120 / 60 = 2 rotati…
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An object weighing 100 lbs is sitting on a frictionless inclined plane that makes a 30° angle with the horizontal. What force, applied parallel to the incline, is needed to keep the object from sliding down?
- 100 lbs
- 50 lbs ✓
- 0 lbs
- 200 lbs
On a frictionless incline, the component of weight parallel to the incline pulls the object downward along the slope. This component = W × sin(θ), where W = weight and θ = incline angle. For 100 lbs at 30°: parallel force = 100 × sin(30°) = 100 × 0.5 = 50 lbs. To prevent sliding, an equal opposing f…
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Two objects of different mass fall from the same height in a vacuum (no air resistance). Which hits the ground first?
- The heavier object
- They hit at the same time — gravity accelerates all objects equally regardless of mass ✓
- The lighter object
- Cannot determine
Galileo's principle (verified famously on the moon by Apollo 15's David Scott dropping a hammer and a feather): in a vacuum, all objects fall with the same acceleration regardless of mass. Acceleration due to gravity on Earth: g = 9.8 m/s² (≈ 32 ft/s²). This is because gravitational force on an obje…
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Two hydraulic pistons are connected. The small piston has an area of 2 sq in and the large piston has an area of 20 sq in. If 100 lbs of force is applied to the small piston, what force is exerted by the large piston?
- 100 lbs
- 1000 lbs ✓
- 10 lbs
- 200 lbs
Pascal's principle: pressure applied to a confined fluid is transmitted equally throughout the fluid. Pressure = Force / Area. In a hydraulic system, pressure is the same in both pistons; force differs based on area. P = F/A is constant: F₁/A₁ = F₂/A₂. Calculation: F₁/A₁ = 100/2 = 50 psi. F₂ = P × A…
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Why does a ship made of steel (denser than water) float?
- Steel is actually less dense than water
- The ship's overall shape displaces a volume of water whose weight equals the ship's weight; the average density of the ship (including hollow interior) is less than water — Archimedes' principle ✓
- Ships only float in salt water
- Magic
Archimedes' principle (3rd century BC): a body fully or partially submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. An object floats when the buoyant force equals its weight. A solid block of steel has density ~7,850 kg/m³, much denser than water…
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A beam is supported at both ends and a 200-lb weight is placed exactly in the middle. How much weight does each support hold?
- 200 lbs each
- 100 lbs each ✓
- 50 lbs each
- 400 lbs each
For a symmetric load on a symmetrically supported beam, each support carries half the load. 200 lbs / 2 = 100 lbs at each support. (Note: this assumes the beam's own weight is negligible; if the beam itself weighs 50 lbs, then each support holds 100 + 25 = 125 lbs.) For ASYMMETRIC loads, use the lev…
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A man lifts a 50-lb box vertically 4 feet. How much work does he do?
- 50 ft-lbs
- 200 ft-lbs ✓
- 12.5 ft-lbs
- 100 ft-lbs
Work = Force × Distance (when force and distance are in the same direction). Here: 50 lbs × 4 ft = 200 ft-lbs of work. Units: in US customary, ft-lbs; in SI, Joules (1 J = 1 N·m); 1 ft-lb ≈ 1.356 J. Work principles: (1) Only force IN THE DIRECTION OF MOTION does work. Carrying a box horizontally at …
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A screw with 10 threads per inch is used to lift a heavy load. If the handle is turned through one full revolution, how far does the screw advance into the material?
- 1 inch
- 1/10 inch (0.1 inch) ✓
- 10 inches
- 1/2 inch
Screw pitch = distance the screw advances per revolution = 1 / (threads per inch). 10 threads per inch → pitch = 1/10 = 0.1 inch per revolution. A screw is essentially an inclined plane wrapped around a cylinder. Mechanical advantage of a screw = (2π × radius of handle/screw) / pitch. Example: a scr…
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A 5 kg object is pushed across a level floor with a force of 20 Newtons. What is its acceleration? (Ignore friction.)
- 4 m/s² ✓
- 100 m/s²
- 0.25 m/s²
- 15 m/s²
Newton's Second Law: F = ma. Solve for a: a = F/m = 20 N / 5 kg = 4 m/s². Always check units: Newton = kg·m/s², so N/kg = m/s² ✓. Common ASVAB MC F=ma scenarios: (1) Given mass and acceleration, find force; (2) Given force and mass, find acceleration (this question); (3) Given force and acceleration…
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Liquids and gases differ in that:
- Liquids cannot be compressed but gases can be compressed; liquids have a definite volume but take the shape of their container, while gases expand to fill their entire container ✓
- Liquids and gases behave identically
- Gases have a fixed volume
- Liquids expand to fill their container
States of matter properties: SOLID — fixed shape and volume; particles vibrate in place; strong intermolecular forces; nearly incompressible. LIQUID — fixed volume, no fixed shape (takes container shape); particles flow past each other; moderate intermolecular forces; nearly incompressible (compress…
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Which shape is generally considered the strongest for structural support?
- Square
- Triangle — its three sides cannot be deformed without changing the length of a side, making it inherently rigid ✓
- Circle
- Rectangle
The triangle is the strongest fundamental shape because it's the only polygon that cannot deform without bending or breaking a side. A square or rectangle can collapse into a parallelogram (the angles change while side lengths remain constant). A triangle's three fixed sides constrain its three angl…
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A pendulum swings back and forth. At what point in its swing is its kinetic energy greatest?
- At the highest point of its swing
- At the lowest point of its swing (the bottom of the arc) ✓
- At the middle of its swing on the way up
- Kinetic energy is constant throughout
A pendulum demonstrates the conservation of mechanical energy. Energy converts between gravitational potential energy (PE = mgh) and kinetic energy (KE = ½mv²). At the highest points (the extremes of the swing): the pendulum is momentarily stopped, velocity = 0, so KE = 0. All energy is potential. A…
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A wheel and axle has a wheel with a radius of 12 inches and an axle with a radius of 3 inches. If a force of 25 lbs is applied to the wheel, what force is exerted at the axle?
- 25 lbs
- 100 lbs ✓
- 6.25 lbs
- 300 lbs
Wheel and axle is a simple machine where two cylinders of different radii are fixed together and rotate together. Mechanical advantage = radius of wheel / radius of axle = 12/3 = 4. Force at axle = 25 × 4 = 100 lbs. The wheel (larger radius) gets the input force; the axle (smaller radius) outputs th…
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Two objects collide. Object A weighs 10 kg moving at 5 m/s. Object B weighs 5 kg at rest. After the collision they stick together. What is their combined velocity? (Conservation of momentum.)
- 5 m/s
- About 3.33 m/s ✓
- 10 m/s
- 0 m/s
Conservation of momentum: in any collision (elastic or inelastic), total momentum before = total momentum after, IF no external forces act on the system. Momentum p = mass × velocity. Before collision: p_A = 10 × 5 = 50 kg·m/s; p_B = 5 × 0 = 0; total = 50 kg·m/s. After collision (objects stick = per…
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Bernoulli's principle states that as the velocity of a fluid increases:
- Its pressure also increases
- Its pressure decreases ✓
- Its pressure stays the same
- It heats up significantly
Bernoulli's principle (Daniel Bernoulli, 1738): for a flowing fluid, faster flow = lower pressure. Conversely, slower flow = higher pressure. This is a consequence of conservation of energy in flowing fluids: kinetic energy (motion) + pressure energy + gravitational potential energy = constant. Fast…
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Which of the following is NOT one of the six classical simple machines?
- Lever
- Battery ✓
- Wedge
- Screw
The six classical simple machines (Renaissance scientists, building on ancient Greek engineering): (1) LEVER — rigid bar pivoting on a fulcrum; (2) WHEEL AND AXLE — two cylinders of different radii fixed together; (3) PULLEY — wheel with a grooved rim for a rope or cable; (4) INCLINED PLANE — sloped…
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Which type of force is a column under a heavy load primarily experiencing?
- Tension
- Compression ✓
- Shear
- Torsion
A column supporting a load is under COMPRESSION — the force squeezes it from both ends (the load pressing down from above, the foundation pressing up from below). Different structural members experience different primary forces: (1) COMPRESSION — squeezing; columns, pillars, struts, the lower side o…
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Which has more kinetic energy: a 1000 kg car traveling at 10 m/s, or a 500 kg motorcycle traveling at 20 m/s?
- Car
- Motorcycle ✓
- Same
- Cannot determine
Kinetic energy KE = ½mv². Calculate both: CAR: ½ × 1000 × 10² = 500 × 100 = 50,000 J. MOTORCYCLE: ½ × 500 × 20² = 250 × 400 = 100,000 J. Motorcycle has twice the KE despite half the mass — because velocity is SQUARED in the formula. Implications: (1) DOUBLING SPEED quadruples KE (and stopping distan…
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A scuba diver experiences increasing pressure as they descend deeper. Approximately how much does pressure increase per 33 feet (10 meters) of depth in water?
- 1 atmosphere (about 14.7 psi) ✓
- 10 atmospheres
- 0.1 atmosphere
- Pressure does not change with depth
Pressure in a fluid increases with depth at a predictable rate. P = ρgh, where ρ is fluid density, g is gravity, h is depth. For water: ρ = 1000 kg/m³, g = 9.8 m/s². Pressure increase per meter of depth = 1000 × 9.8 = 9800 Pa per meter ≈ 9.8 kPa/m ≈ 1.4 psi/m. So 33 feet (10 meters) ≈ 14 psi pressur…
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Two gears mesh together. Gear A rotates clockwise. Which direction does gear B rotate?
- Also clockwise
- Counterclockwise (opposite direction) ✓
- It depends on the size of the gears
- Both directions simultaneously
MESHING gears rotate in OPPOSITE directions. Their teeth interlock at the contact point; as one gear pushes its tooth into the other, that contact point on each gear must move in the same linear direction at that instant — but since they're rotating around different axes, this means opposite rotatio…
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What is the difference between mass and weight?
- They are the same thing
- Mass is the amount of matter in an object (measured in kg or slug, constant everywhere); weight is the force of gravity on that mass (measured in N or lb-force, varies with location) ✓
- Mass is for solids, weight is for liquids
- Weight is only for very heavy objects
Mass and weight are fundamentally different concepts often confused. MASS: amount of matter; intrinsic property; constant regardless of location; SI unit: kilogram (kg); US: slug (rare) or pound-mass (lbm); measured with a BALANCE (compares to known masses). WEIGHT: gravitational force on mass; depe…
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Which is the strongest type of bridge structure for spanning long distances?
- Beam bridge
- Suspension or cable-stayed bridges, which use steel cables in tension to support the deck over very long spans ✓
- All bridge types span equal distances
- Stone bridges
Bridge types, ranked roughly by typical span: (1) BEAM BRIDGES — simplest, like a board across a stream; load creates bending; relatively short spans (typically <100m); examples: many highway overpasses; (2) ARCH BRIDGES — convert load to compression along the curve, transferring to abutments; spans…
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A motor lifts a 100 kg load 5 meters in 10 seconds. What is the motor's power output? (g = 10 m/s² for simplicity)
- 500 W ✓
- 5000 W
- 50 W
- 500 J
Power = Work / Time. Work = Force × Distance = (mg) × h = 100 × 10 × 5 = 5000 J (joules). Power = 5000 J / 10 s = 500 W (watts). Power units: WATT = Joule per second (SI standard); 1 kW = 1000 W; 1 MW = 1,000,000 W; HORSEPOWER (hp) = 746 W (or 550 ft-lb/s); 1 hp ≈ 0.75 kW. Common comparisons: human …
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A lever has a 6-foot effort arm and a 2-foot load arm. What is the mechanical advantage?
MA (lever) = effort arm ÷ load arm = 6 ÷ 2 = 3. A mechanical advantage of 3 means 1 pound of effort lifts 3 pounds of load.
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A small gear with 10 teeth drives a large gear with 40 teeth. If the small gear rotates at 200 RPM, what is the large gear's speed?
- 25 RPM
- 50 RPM ✓
- 100 RPM
- 800 RPM
Gear ratio = driver teeth / driven teeth = 10/40 = 1/4. Large gear speed = 200 × (10/40) = 200 × 0.25 = 50 RPM.
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An object weighs 150 lbs on Earth. What is its approximate weight on the Moon (1/6 of Earth's gravity)?
- 6 lbs
- 12 lbs
- 25 lbs ✓
- 30 lbs
Weight on Moon = 150 ÷ 6 = 25 lbs. Weight depends on gravity; mass remains constant but weight changes with gravitational force.
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A wheel-and-axle system has a wheel radius of 12 inches and an axle radius of 3 inches. What is the mechanical advantage?
MA (wheel and axle) = wheel radius ÷ axle radius = 12 ÷ 3 = 4.
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Which of the following statements about friction is correct?
- Friction always increases speed
- Friction converts kinetic energy to heat ✓
- Friction only occurs between liquids
- Friction is eliminated by rough surfaces
Friction converts kinetic energy (motion energy) to thermal energy (heat). When you rub your hands together, friction converts motion to warmth. Friction opposes relative motion between surfaces in contact.
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A hydraulic press has a small piston with area 2 cm² and a large piston with area 20 cm². If 10 N of force is applied to the small piston, what force does the large piston exert?
PASCAL'S PRINCIPLE: In a closed fluid system, pressure is transmitted equally in all directions. Pressure = Force ÷ Area. Small piston: P = 10N ÷ 2cm² = 5 N/cm². Same pressure at large piston: Force = P × Area = 5 N/cm² × 20 cm² = 100 N. MECHANICAL ADVANTAGE = large area ÷ small area = 20/2 = 10. In…
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Two objects collide and stick together. Object A (2 kg, 6 m/s) hits stationary Object B (4 kg). What is their combined velocity after the collision?
- 1 m/s
- 2 m/s ✓
- 3 m/s
- 6 m/s
CONSERVATION OF MOMENTUM (perfectly inelastic collision): Total momentum before = Total momentum after. Momentum = mass × velocity. Before: Object A: 2 kg × 6 m/s = 12 kg·m/s; Object B: 4 kg × 0 = 0. Total before: 12 kg·m/s. After: Combined mass = 2 + 4 = 6 kg. 6 kg × v = 12 kg·m/s. v = 12 ÷ 6 = 2 m…
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A submarine dives from the surface to 100 meters. How does the water pressure on the submarine change?
- Pressure stays the same
- Pressure decreases
- Pressure increases approximately 10 times — water pressure increases by roughly 1 atmosphere (14.7 psi) for every 10 metres of depth ✓
- Pressure only changes if the submarine moves quickly
HYDROSTATIC PRESSURE: Water pressure increases with depth because of the weight of water above. RULE OF THUMB: Pressure increases by approximately 1 atmosphere (atm) or 14.7 psi for every 10 metres (33 feet) of seawater depth. At the surface: 1 atm (atmospheric pressure). At 10 m: 2 atm total. At 10…
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A screw has 30 threads per inch. How far does it advance into a material when turned 3 full rotations?
- 0.05 inches
- 0.10 inches ✓
- 0.30 inches
- 3 inches
SCREW PITCH: 30 threads per inch means each full rotation advances the screw 1/30 inch. 3 rotations × (1/30 inch per rotation) = 3/30 = 0.10 inches. The screw is a simple machine (inclined plane wrapped around a cylinder) that converts rotational force (torque) into linear force and motion. MORE THR…
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Which material property describes a metal's ability to be drawn into wire without breaking?
- Hardness
- Ductility — the ability to be permanently deformed (stretched into wire) without fracturing; copper, gold, and aluminium are highly ductile; cast iron is brittle (not ductile) ✓
- Elasticity
- Brittleness
MATERIAL PROPERTIES for the ASVAB: DUCTILITY: Ability to be drawn into wire or stretched without breaking (copper wire, gold wire); MALLEABILITY: Ability to be hammered or rolled into sheets without breaking (gold leaf, aluminium foil) — similar to ductility but in compression/bending rather than te…
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In a first-class lever (like a seesaw), where is the fulcrum located?
- At one end
- Between the effort (force) and the load ✓
- At the load
- There is no fulcrum
In a FIRST-CLASS LEVER, the FULCRUM is located BETWEEN the effort (applied force) and the load — like a seesaw or a pair of scissors. ASVAB Mechanical Comprehension tests the three classes of levers: FIRST-CLASS: fulcrum in the middle (seesaw, crowbar, scissors); SECOND-CLASS: load in the middle (wh…
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Two meshed gears turn in what directions relative to each other?
- The same direction
- Opposite directions ✓
- Both stop
- Random directions
Two directly MESHED (interlocking) gears turn in OPPOSITE directions — if one turns clockwise, the other turns counterclockwise. ASVAB Mechanical Comprehension tests gear systems. GEAR DIRECTION: adjacent meshed gears always rotate oppositely. GEAR RATIO/SPEED: a smaller gear driving a larger gear t…
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What is the main advantage of using a system of multiple pulleys?
- It makes the load heavier
- It reduces the amount of force needed to lift a load (provides mechanical advantage) ✓
- It has no effect
- It speeds up the lift only
A system of MULTIPLE PULLEYS reduces the FORCE needed to lift a load by providing MECHANICAL ADVANTAGE. ASVAB Mechanical Comprehension tests pulleys. A single fixed pulley just changes the direction of force (no force reduction). Adding movable pulleys (a block and tackle) reduces the force needed —…
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A heavy box sits on the floor and does not move. The force preventing it from sliding when pushed gently is:
- Gravity
- Friction ✓
- Magnetism
- Tension
FRICTION is the force that resists the sliding motion between the box and the floor, preventing it from moving when pushed gently. ASVAB Mechanical Comprehension tests forces. FRICTION opposes motion between surfaces in contact; STATIC friction holds an object still until enough force overcomes it; …
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An inclined plane (ramp) makes lifting a heavy object easier by:
- Eliminating the need for force
- Reducing the force needed by increasing the distance over which the force is applied ✓
- Making the object lighter
- Increasing gravity
An INCLINED PLANE (ramp) reduces the FORCE needed to raise an object by spreading the work over a greater DISTANCE. ASVAB Mechanical Comprehension tests simple machines. Instead of lifting straight up (high force, short distance), you push up the ramp (less force, longer distance) — the work (force …
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Hydraulic systems (like a car's brakes) work based on the principle that:
- Liquids can be compressed easily
- Pressure applied to a confined liquid is transmitted equally throughout the liquid ✓
- Liquids weigh nothing
- Force decreases through liquids
HYDRAULIC SYSTEMS work on PASCAL'S PRINCIPLE: pressure applied to a confined (enclosed) liquid is transmitted EQUALLY throughout the liquid in all directions. ASVAB Mechanical Comprehension tests hydraulics. Because liquids are nearly INCOMPRESSIBLE, force applied at one point (a small piston) is tr…
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A small gear with 10 teeth drives a large gear with 30 teeth. For every 3 turns of the small gear, the large gear turns:
- 9 times
- 1 time ✓
- 3 times
- 30 times
The large gear turns 1 time. ASVAB Mechanical Comprehension tests gear ratios. The gear ratio = driven gear teeth ÷ drive gear teeth = 30 ÷ 10 = 3:1. This means the small (drive) gear must turn 3 times for the large (driven) gear to turn ONCE. So for 3 turns of the small gear, the large gear turns 3…
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To lift a heavy load with a lever using the least effort, where should you apply the force, and where should the fulcrum be?
- Apply force close to the fulcrum
- Apply force far from the fulcrum, with the fulcrum close to the load ✓
- Apply force at the fulcrum
- The positions don't matter
To minimize effort with a lever: apply the force FAR from the fulcrum (long effort arm) and place the fulcrum CLOSE to the load (short load arm). ASVAB Mechanical Comprehension tests lever mechanical advantage. MECHANICAL ADVANTAGE = effort arm length ÷ load arm length. A longer effort arm and short…
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Two people push on opposite sides of a box with equal force. What happens to the box?
- It moves toward the stronger person
- It remains stationary because the forces are balanced (net force is zero) ✓
- It spins rapidly
- It moves upward
The box remains STATIONARY because the equal, opposite forces are BALANCED — the NET FORCE is zero. ASVAB Mechanical Comprehension tests force balance. When forces are balanced (equal and opposite), there is no net force, so there's no change in motion (Newton's first law — an object stays at rest).…
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A screw is essentially which simple machine wrapped around a cylinder?
- A lever
- An inclined plane ✓
- A pulley
- A wheel and axle
A SCREW is essentially an INCLINED PLANE wrapped around a cylinder. ASVAB Mechanical Comprehension tests simple machines. The threads of a screw form a spiral inclined plane; turning the screw converts rotational motion into linear motion and provides mechanical advantage (a screw with closer thread…
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A sharp knife cuts better than a dull one because the sharp edge:
- Is heavier
- Concentrates the force over a smaller area, increasing pressure ✓
- Has less friction
- Is magnetic
A SHARP knife cuts better because its thin edge CONCENTRATES the force over a SMALLER AREA, increasing the PRESSURE. ASVAB Mechanical Comprehension tests pressure (PRESSURE = FORCE ÷ AREA). The same force applied over a smaller area produces greater pressure, allowing the blade to cut. A dull knife …
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A ball held at the top of a hill has the most of which type of energy, before it is released?
- Kinetic energy
- Potential energy ✓
- Thermal energy
- Electrical energy
A ball held at the top of a hill has maximum POTENTIAL ENERGY (specifically gravitational potential energy due to its height/position). ASVAB Mechanical Comprehension tests energy. POTENTIAL ENERGY is stored energy due to position (the higher up, the more); KINETIC ENERGY is energy of motion. As the…
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If you want to increase the speed of a driven gear, the drive gear should be:
- Larger than the driven gear ✓
- Smaller than the driven gear
- The same size as the driven gear
- Removed entirely
To INCREASE the SPEED of the driven gear, the drive gear should be LARGER than the driven gear. ASVAB Mechanical Comprehension tests gear speed relationships. When a LARGER drive gear turns a SMALLER driven gear, the smaller gear spins FASTER (more rotations) but with LESS torque. Conversely, a smal…
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Which shape is generally considered the strongest and most stable for distributing weight and resisting deformation?
- A square
- A triangle ✓
- A circle
- A rectangle
The TRIANGLE is generally the strongest, most stable shape for distributing weight and resisting deformation. ASVAB Mechanical Comprehension includes structural concepts. A triangle's rigid shape distributes force along its sides and cannot be deformed without changing the length of a side — making …
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Why does a heavy steel ship float while a small steel bolt sinks?
- The ship is made of lighter steel
- The ship's shape displaces enough water to create buoyancy equal to its weight, while the dense bolt displaces little water ✓
- Ships have no weight
- The bolt is heavier than the ship
A steel SHIP floats because its hollow SHAPE DISPLACES a large volume of water, creating an upward BUOYANT FORCE equal to the ship's weight (Archimedes' principle); a solid steel BOLT displaces very little water, so its buoyant force is less than its weight, and it sinks. ASVAB Mechanical Comprehens…
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In a first-class lever (like a seesaw), where is the fulcrum located?
- At one end, beyond the load
- Between the effort (force) and the load ✓
- At the same point as the effort
- There is no fulcrum
In a first-class lever, the fulcrum (pivot point) is located between the effort (the force you apply) and the load (the resistance you move) — like a seesaw or a pair of scissors. This arrangement can multiply force or change its direction. The other lever classes differ in arrangement: in a second-…
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How does a single fixed pulley help when lifting a load?
- It reduces the force needed by half
- It changes the direction of the force without reducing the amount of force needed ✓
- It doubles the load
- It removes the need for any force
A single fixed pulley (attached to a fixed point overhead) changes the direction of the force — letting you pull down to lift a load up — but it does not reduce the amount of force required; you still must pull with a force equal to the load's weight. To gain a mechanical advantage (reduce the force…
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When two gears of different sizes mesh together, what happens to the smaller gear compared to the larger gear?
- The smaller gear turns slower
- The smaller gear turns faster but with less torque than the larger gear ✓
- Both turn at exactly the same speed
- The smaller gear does not turn
When a small gear meshes with a larger gear, the smaller gear turns faster but with less torque, while the larger gear turns slower but with more torque. This is because the teeth move at the same rate where they mesh, so the smaller gear must complete more revolutions to keep up. Gears trade speed …
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What is friction?
- A force that helps objects move faster
- A force that opposes motion between two surfaces in contact ✓
- A type of gravity
- The weight of an object
Friction is a force that opposes the motion (or attempted motion) of two surfaces that are in contact with each other. It acts in the direction opposite to movement and depends on the nature of the surfaces and how hard they press together. Friction can be useful (it lets tires grip the road and bra…
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According to the principle of inertia, what will a moving object do unless a force acts on it?
- Stop on its own
- Continue moving in a straight line at a constant speed ✓
- Speed up
- Curve to the right
Inertia is the tendency of an object to resist changes in its state of motion (Newton's first law). An object in motion will continue moving in a straight line at a constant speed unless an unbalanced force acts on it, and an object at rest will stay at rest unless a force moves it. In everyday life…
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According to Pascal's principle, how does pressure applied to a confined fluid behave?
- It is lost immediately
- It is transmitted equally in all directions throughout the fluid ✓
- It only pushes downward
- It increases the fluid's temperature
Pascal's principle states that pressure applied to a confined (enclosed) fluid is transmitted equally and undiminished in all directions throughout the fluid. This is the basis of hydraulic systems: a small force applied to a small piston creates pressure that acts on a larger piston, producing a la…
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In a hydraulic system, applying a small force to a small piston can produce a large force on a large piston. Why?
- The fluid creates energy
- Because pressure is the same throughout, the larger piston's greater area produces a proportionally larger force ✓
- The small piston is stronger
- Large pistons need no force
In a hydraulic system, pressure (force per unit area) is transmitted equally through the fluid (Pascal's principle). Since pressure equals force divided by area, the same pressure acting on a larger piston area produces a larger force: F = pressure × area. So a small force on a small-area piston cre…
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When a load is placed in the middle of a beam supported at both ends, where is the beam under the greatest stress?
- At the supports only
- In the middle, where the load is applied ✓
- At the very top corners
- Nowhere; the load spreads out evenly
When a beam is supported at both ends and a load is placed in the middle, the greatest bending stress occurs at the center, directly under the load, where the beam tends to sag the most. The bottom of the beam at the middle is in tension (stretched) while the top is in compression (squeezed). This i…
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In physics, when is mechanical work done on an object?
- Whenever a force is applied, even if nothing moves
- When a force causes an object to move in the direction of the force ✓
- Only when an object is lifted
- Only when an object speeds up
In physics, work is done when a force causes an object to move in the direction of that force; work equals force multiplied by the distance moved in the force's direction (W = F × d). If you push on a wall and it doesn't move, you exert force but do no mechanical work because there is no displacemen…
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What is the relationship between work and power?
- They are the same thing
- Power is the rate at which work is done (work divided by time) ✓
- Power is work multiplied by distance
- Work is power divided by force
Power is the rate at which work is done — that is, the amount of work divided by the time taken (Power = Work ÷ Time). Two machines might do the same amount of work, but the one that does it faster has more power. For example, two motors that each lift the same load to the same height do equal work,…
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How does an inclined plane (ramp) make lifting a heavy object easier?
- It reduces the object's weight
- It reduces the force needed by spreading the work over a longer distance ✓
- It removes gravity
- It makes the object lighter permanently
An inclined plane (ramp) makes raising a heavy object easier by reducing the force needed to move it — but over a longer distance. Instead of lifting the full weight straight up, you push it up the gentler slope with less force, though you must move it farther. The total work (force × distance) is a…
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Two objects are dropped from the same height at the same time, one heavier than the other. Ignoring air resistance, which hits the ground first?
- The heavier object
- The lighter object
- They hit at the same time ✓
- Neither falls
Ignoring air resistance, all objects fall with the same acceleration due to gravity (about 9.8 m/s²) regardless of their mass, so two objects dropped from the same height at the same time hit the ground at the same moment. This famous principle means a heavy ball and a light ball fall together in a …
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Why is a triangle considered the strongest and most stable shape used in structures like bridges and towers?
- It uses the least material
- Its fixed angles and rigid sides resist deformation, so it does not collapse or shift under load like a square can ✓
- It is the lightest shape
- Triangles are decorative only
A triangle is the most stable shape in construction because its three fixed sides and angles cannot change shape without one of the sides changing length — it is inherently rigid. A square or rectangle, by contrast, can collapse into a parallelogram (rack sideways) under load unless it is braced, of…
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Why does an object feel lighter when submerged in water?
- Water removes the object's mass
- The water exerts an upward buoyant force on the object ✓
- Gravity stops working underwater
- The object actually weighs more
An object feels lighter in water because the water exerts an upward buoyant force on it. According to Archimedes' principle, this buoyant force equals the weight of the fluid the object displaces. The buoyant force partially counteracts gravity, so the object's apparent weight is reduced. If the buo…
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What is mechanical advantage?
- The speed of a machine
- The factor by which a machine multiplies the input force ✓
- The weight of a machine
- The energy a machine creates
Mechanical advantage is the factor by which a simple machine multiplies the input (effort) force. For example, a mechanical advantage of 4 means the machine outputs four times the force you put in. It is calculated as the output force divided by the input force (or, ideally, the distance the effort …