AP Physics 1 practice questions and exam guide

A power output of 1500 W lifts a 50-kg load. The maximum steady speed (g = 10 m/s²)?

1. 3 m/s (= P/(mg))
2. 30 m/s
3. 0.3 m/s
4. 15 m/s

Answer: A — 3 m/s (= P/(mg))

A) P = F·v = mg·v → v = 1500/500 = 3 m/s. B/D) Arithmetic. C) Off by factor 10.

Newton's second law in vector form is:

1. ∑F = ma — net force equals mass times acceleration
2. F = mv
3. ∑F = m/v
4. ∑F = ½mv²

Answer: A — ∑F = ma — net force equals mass times acceleration

A) Standard form. B) Momentum. C) Nonsense. D) Kinetic energy.

A 1000 kg car moving at 20 m/s collides with and sticks to a stationary 2000 kg truck. The combined velocity after collision is (perfectly inelastic):

1. 6.67 m/s
2. 10 m/s
3. 13.3 m/s
4. 20 m/s

Answer: A — 6.67 m/s

Conservation of momentum (no external force): m₁v₁ + m₂v₂ = (m₁ + m₂)v'. (1000)(20) + (2000)(0) = (3000)v'. v' = 20,000/3000 ≈ 6.67 m/s. KE is NOT conserved in inelastic collisions (some converts to heat/sound/deformation).

Sound waves in air are:

1. Transverse (oscillation perpendicular to propagation)
2. Electromagnetic
3. Longitudinal (compressions and rarefactions along propagation)
4. Standing waves

Answer: C — Longitudinal (compressions and rarefactions along propagation)

C) Air can't sustain shear → sound is longitudinal. A) Transverse waves on strings, EM. B) Sound is mechanical. D) Special case.

A 4-kg block at the top of a 2-m frictionless incline starts at rest. Speed at the bottom (g = 10 m/s²)?

1. 6.32 m/s (= √(2gh))
2. 4 m/s
3. 20 m/s
4. 8 m/s

Answer: A — 6.32 m/s (= √(2gh))

A) v = √(2·10·2) = √40 ≈ 6.32 m/s. Mass cancels. B/C/D) Arithmetic mistakes.

A wheel speeds up from rest to 20 rad/s in 4 s. Angular acceleration?

1. 80 rad/s²
2. 5 rad/s² (= Δω/Δt)
3. 0.2 rad/s²
4. 16 rad/s²

Answer: B — 5 rad/s² (= Δω/Δt)

B) α = (20 − 0)/4 = 5 rad/s². A) Multiplies. C) Inverse. D) Wrong.

A car turns left on a level road. The direction of friction on the tires is:

1. Forward
2. Backward
3. Leftward (toward the center of the turn — centripetal)
4. Outward (centrifugal)

Answer: C — Leftward (toward the center of the turn — centripetal)

C) Friction provides centripetal force directed toward circle center. D) 'Centrifugal' is a pseudo-force; real friction acts inward. A/B) Not the turning direction.

A rock has mass 2 kg in air and weighs 14 N when submerged in water (g = 10 m/s²). Buoyant force?

1. 6 N (= mg − apparent weight)
2. 14 N
3. 20 N
4. 34 N

Answer: A — 6 N (= mg − apparent weight)

A) F_b = W_actual − W_apparent = 20 − 14 = 6 N. B) Apparent weight. C) Actual weight. D) Sum.

An object moving in the +x direction has acceleration in the −x direction. The object is:

1. Speeding up
2. Slowing down (decelerating)
3. At rest
4. Reversing direction at constant speed

Answer: B — Slowing down (decelerating)

B) When v and a have opposite signs, the object slows. A) Same signs would speed up. C) Both would be zero. D) Eventually reverses, but at the moment described it's slowing.

Pressure at depth 10 m below a fresh-water surface (ρ = 1000 kg/m³; g = 10 m/s²)?

1. 1,000 Pa
2. 1 Pa
3. 10,000 Pa
4. 100,000 Pa = 100 kPa gauge (= ρgh)

Answer: D — 100,000 Pa = 100 kPa gauge (= ρgh)

D) P = ρgh = 1000·10·10 = 100,000 Pa = 1 atm gauge. A/B/C) Wrong factors.

A pendulum of length L has period T = 2π√(L/g). If L is quadrupled, the new period is:

1. T/2
2. T (unchanged)
3. 2T (period scales with √L)
4. 4T

Answer: C — 2T (period scales with √L)

T ∝ √L. Quadrupling L doubles T (√4 = 2). Period is independent of mass and amplitude (small-angle approximation). (D) Linear scaling (wrong). (A) Inverse (wrong).

A solid disk and a hollow ring with the same mass and radius roll down the same incline (without slipping). Which reaches the bottom first?

1. They tie
2. The slower one
3. The ring (more rotational inertia helps)
4. The disk (less of its mass at the rim → smaller I → more of total energy goes to translational KE rather than rotational KE)

Answer: D — The disk (less of its mass at the rim → smaller I → more of total energy goes to translational KE rather than rotational KE)

Total KE = (1/2)mv² + (1/2)Iω². With rolling constraint ω = v/r, more I means less v at the bottom. Disk I = (1/2)mr², ring I = mr². Disk has less I, so it goes faster. Common classroom demonstration. Mathematical result: a/g = sin θ / (1 + I/(mr²)).

What is gravitational potential energy near Earth?

U_g = mgh, where h is height above a reference.

Banked curve angle for friction-free turn?

tan θ = v²/(rg).

Why do you bend your knees when landing?

Increases time over which momentum changes — reduces force on body (impulse-momentum).

A ball is thrown horizontally at 10 m/s from a 20-m cliff. Time to land?

20 = ½(9.8)t² → t ≈ 2.02 s.

Velocity at top of vertical motion (no air resistance)?

Zero, instantaneously. Acceleration is still −g.

What is the period of a 1-m pendulum on Earth?

T = 2π√(1/9.8) ≈ 2.0 s.