Free Falling

Question 1

During free fall, the acceleration of an object depends on:

Accepted Answer

Neither mass nor shape (ignoring air) — Ignoring air resistance, all objects fall with the same g.

Question 2

The approximate value of gravitational acceleration g is:

Accepted Answer

9.81 m s⁻² — g ≈ 9.81 m s⁻² near the Earth's surface.

Question 3

A ball is dropped from rest. Its initial velocity u is:

Accepted Answer

0 — A dropped object starts from rest, u = 0.

Question 4

A ball dropped from rest falls for 2 s (g = 10 m s⁻²). Its velocity is:

Accepted Answer

20 m s⁻¹ — v = gt = 10 × 2 = 20 m s⁻¹.

Question 5

A stone falls from rest for 3 s (g = 10 m s⁻²). The height fallen is:

Accepted Answer

45 m — h = ½gt² = ½ × 10 × 9 = 45 m.

Question 6

At the highest point of an object thrown straight up, its velocity is:

Accepted Answer

Zero — The object stops momentarily at maximum height, v = 0.

Question 7

In a vacuum, a feather and a hammer dropped together will:

Accepted Answer

They land at the same time — Without air resistance both have the same acceleration g.

Question 8

A ball is thrown up at 20 m s⁻¹ (g = 10 m s⁻²). Time to reach the top is:

Accepted Answer

2 s — At the top v = 0: 0 = 20 − 10t, t = 2 s.

Question 9

Using v² = u² + 2gh, a stone dropped from 20 m (g = 10 m s⁻²) hits the ground at:

Accepted Answer

20 m s⁻¹ — v² = 0 + 2(10)(20) = 400, v = 20 m s⁻¹.

Question 10

The force responsible for free fall is:

Accepted Answer

Gravity — Free fall occurs under gravity alone.