Figure 9 shows a small steel ball held at a height, h, above the ground - Edexcel - GCSE Physics Combined Science - Question 5 - 2021 - Paper 1

One possible reason is that the students may have reacted too slowly in starting or stopping the stopwatch, leading to an inaccurate measurement of the fall time.

An improvement could be to use light gates to automatically start and stop the timing, eliminating human reaction time errors.

Using the formula for force:

$\text{force} = \frac{\text{change in momentum}}{\text{time}}$

The change in momentum is equal to the momentum just before it hits the floor, which is 8.7 kg m/s:

$\text{force} = \frac{8.7}{0.35}$

Calculating:

$\text{force} = 24.857 \approx 25 \text{ N}$

Magnitude: 25 N Direction: Downwards, towards the floor.

Using the formula for momentum:

$\text{momentum} = \text{mass} \times \text{velocity}$

We can rearrange for mass:

$\text{mass} = \frac{\text{momentum}}{\text{velocity}}$

Substituting the values:

$\text{mass} = \frac{0.40}{v}$

To find the velocity at S, we need to assume it was released from rest. Without additional specific information on the velocity at that point, we can only present mass calculations based on further data.