A 5 kg object is pushed across a level floor with a force of 20 Newtons. What is its acceleration? (Ignore friction.)

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, find mass; (4) With friction or other opposing forces, NET force = ma. Example with friction: if friction force = 5 N opposing the 20 N push, net force = 15 N, acceleration = 15/5 = 3 m/s². Force units: Newton (SI, kg·m/s²) or pound-force (US customary, kg slugs × ft/s²). Mass vs weight: mass is matter (kg); weight is the force of gravity on mass (W = mg, in N). A 5 kg object weighs 5 × 9.8 = 49 N on Earth, 5 × 1.6 = 8 N on the Moon. Pounds: 'lb' often refers to weight (pound-force, lbf) but sometimes mass (pound-mass, lbm); ASVAB usually uses pounds as weight. Conversions: 1 kg ≈ 2.2 lbs; 1 lb ≈ 4.45 N. Friction: static friction prevents motion (up to a maximum); kinetic friction acts on moving objects (usually less than max static). Coefficient of friction (μ) × normal force = friction force. ASVAB MC may include friction conceptually but rarely calculation with μ.