Question

A man drops a 10kg rock from the top of a 20m ladder. What will be its kinetic energy when it reaches the ground? What will be its speed just before it hits the ground? ( take g = 10m/s 2

Answer 1

The answer is in above image


Hope it helps ^_^

Answer 2

Answer:

2000J

Explanation:

initial velocity of the rock = 0m/s

acceleration due to gravity = 10m/s²

mass of the rock = 10 kg

height from which it is dropped = 20m

By using the 3rd equation of motion:

v² = u² + 2gh

v² = (0)² + 2(10)(20)

v²= 400

v = square root of 400 = 20 m/s

Ek = 1/2mv²

= 1/2 × 10 × 20 × 20 = 5 × 400 = 2000 J

Thus the kinetic energy of the rock when it reaches the ground is 2000 J