Hailstones are small balls of ice - AQA - GCSE Physics - Question 4 - 2022 - Paper 1

As the hailstone falls, its velocity increases, causing air resistance to increase. Eventually, the air resistance becomes equal to the weight of the hailstone, leading to a resultant force of zero. At this point, the hailstone stops accelerating and continues to fall at a constant terminal velocity.

Terminal velocity increases with mass because as mass increases, the weight of the hailstone also increases. Since terminal velocity occurs when the weight equals the air resistance, a heavier hailstone will have a greater terminal velocity.

The maximum kinetic energy (KE) is given by the formula $E_k = \frac{1}{2} mv^2$. A hailstone with a mass of 10 g has a certain maximum velocity before reaching terminal velocity, whereas a 20 g hailstone will have a greater weight and, hence, a higher maximum velocity. Since kinetic energy depends on both mass and the square of velocity, the 20 g hailstone will possess significantly more kinetic energy than the 10 g hailstone, proportionate to the increase in both mass and velocity at terminal conditions.

1 J is equivalent to 1 N m.

To determine the average force, we use the formula:

$F = \frac{mv}{t}$

where the mass is 0.0185 kg, the terminal velocity is 25 m/s, and the time taken is 0.060 s.

Substituting the values:

$F = \frac{0.0185 \, \text{kg} \times 25 \, \text{m/s}}{0.060 \, \text{s}} = 7.708 \, \text{N}$

Thus, the average force on the hailstone is approximately 7.71 N.