Question

A ball of mass 300 g is dropped from a height of 10 m and penetrates 1.5 m into sand. Find the average resistance by the sand. Take \( g = 10\ \text{m/s}^2 \).

• A. 35 N
• B. 23 N
• C. 34 N
• D. 28 N

Hint:

Use \( mgh = Fd \) when work-energy theorem is applicable.

Answer 1

The Correct Option is B

Use energy conservation: Loss in kinetic energy = Work done by sand \[ mgh = Fd \Rightarrow 0.3 \cdot 10 \cdot 10 = F \cdot 1.5 \Rightarrow F = \frac{30}{1.5} = 20\ \text{N} \] Total resistance = mg + extra resistive force \[ = 3 + 20 = 23\ \text{N} \]