Question

A copper ball is dropped from a vertical height of 1200 m. If the initial temperature of copper ball at the height is 12°C, what is its temperature on reaching the ground? Assume all its kinetic energy changes to heat energy and sp. heat capacity of copper is 400 Jkg⁻¹°C⁻¹ and g = 10 ms⁻².

Answer 1

When the ball falls from height h, it loses gravitational potential energy mgh.

Assuming no energy loss to the surroundings, this energy becomes heat gained by the ball:

mgh = mcΔθ

$$\Delta\theta = \frac{gh}{c}$$

$$= \frac{10 \times 1200}{400}$$

= 30°C

Therefore final temperature = 12°C + 30°C = 42°C