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

The hailstone reaches terminal velocity when the force of air resistance increases as its speed increases until it equals the weight of the hailstone. At this point, the resultant force becomes zero, and the hailstone continues to fall at constant speed.

Terminal velocity increases with mass because as the mass of the hailstone increases, its weight also increases. A heavier hailstone requires a greater force of air resistance to balance this increased weight. Therefore, it can achieve a higher speed before the forces are balanced.

The kinetic energy (E_k) of an object is given by the formula: $E_k = \frac{1}{2} mv^2$
As the mass of the hailstone increases from 10 g (0.01 kg) to 20 g (0.02 kg), the kinetic energy will also increase more than double because kinetic energy is proportional to the mass. Thus, the hailstone with a mass of 20 g will possess greater kinetic energy due to both its greater mass and the higher terminal velocity attained.

1 N m

To determine the average force, we can use the formula: $F = \frac{\Delta v}{\Delta t}$
where (\Delta v = 25 \text{ m/s}) and (\Delta t = 0.060 \text{ s}). Thus,
First, we find the mass in kg: 10 g = 0.01 kg, and with the hailstone's velocity:
$F = 0.01 \text{ kg} \times 25 \text{ m/s} / 0.060 \text{ s} = 4.167 \text{ N}$
The average force on the hailstone as it hit the ground is approximately 4.167 N.