Kinematics: Motion in One and Two Dimensions — High School Physics practice questions

Ignoring air resistance, which launch angle gives a projectile the greatest range on level ground?

1. 90°
2. 30°
3. 45°
4. 60°

Answer: C — 45°

C) Correct — It balances horizontal and vertical motion. A) Goes straight up and lands at the start. B) Gives less range than 45°. D) Gives the same range as 30°.

A car speeds up from 0 to 20 m/s in 4 s. What is its acceleration?

1. 5 m/s²
2. 80 m/s²
3. 0.2 m/s²
4. 20 m/s²

Answer: A — 5 m/s²

A) Correct — a = Δv/Δt = 20/4. B) Multiplies instead of dividing. C) Divides time by velocity. D) Uses the final speed as the acceleration.

A runner covers 100 m in 20 s. What is the average speed?

1. 2,000 m/s
2. 5 m/s
3. 0.2 m/s
4. 80 m/s

Answer: B — 5 m/s

B) Correct — 100 ÷ 20. A) Multiplies instead of dividing. C) Divides time by distance. D) Subtracts.

At the top of its flight, a ball thrown straight up has:

1. zero velocity and zero acceleration
2. zero velocity and 9.8 m/s² downward acceleration
3. maximum velocity
4. upward acceleration

Answer: B — zero velocity and 9.8 m/s² downward acceleration

B) Correct — Gravity keeps acting at the top. A) Gravity doesn't switch off. C) Velocity is zero at the top. D) Gravity pulls down.

A rock is dropped from rest. What is its speed after 3 s? (g = 9.8 m/s²)

1. 29.4 m/s
2. 9.8 m/s
3. 44.1 m
4. 3.3 m/s

Answer: A — 29.4 m/s

A) Correct — v = gt = 9.8 × 3. B) Gives the speed after 1 s. C) Is the distance fallen, not the speed. D) Divides 9.8 by 3.

On a velocity-time graph, the area under the line represents:

1. acceleration
2. force
3. jerk
4. displacement

Answer: D — displacement

D) Correct — Velocity × time = displacement. A) Is the slope. B) Is not shown directly. C) Is the rate of change of acceleration.

One ball is dropped and another is thrown horizontally from the same height at the same time. Which lands first?

1. They land at the same time
2. The dropped ball
3. The thrown ball
4. It depends on their masses

Answer: A — They land at the same time

A) Correct — Vertical motion is the same for both. B) Horizontal speed doesn't affect falling time. C) Horizontal speed doesn't affect falling time. D) Mass doesn't affect falling time without air resistance.

What is the time of flight for a projectile launched at v₀, angle θ, on level ground?

T = 2v₀ sin θ / g.

In projectile motion, what is the vertical acceleration?

g (≈9.8 m/s²) directed downward.

In projectile motion (no air resistance), what is the horizontal acceleration?

Zero. Horizontal velocity is constant.

Why are horizontal and vertical motion analyzed separately for projectiles?

Because they are independent: horizontal has no acceleration, vertical has acceleration g; they share only time.