Andrew skis down a hill - Edexcel - GCSE Physics - Question 2 - 2013 - Paper 1

To determine Andrew's momentum, we can use the formula for momentum, given by

$p = mv$

where:

• $p$ is momentum,
• $m$ is mass,
• $v$ is velocity.

Substituting in the values:

$p = 67 ext{ kg} imes 31 ext{ m/s} = 2077 ext{ kg m/s}$

Thus, Andrew's momentum is approximately 2000 kg m/s.

To find the average force exerted on Andrew while he slows down, we can use the formula:

$F = \frac{\Delta p}{\Delta t}$

where:

• $F$ is the average force,
• $\Delta p$ is the change in momentum,
• $\Delta t$ is the time taken for the change in momentum.

Since his momentum changes from 2000 kg m/s to 0 kg m/s, the change in momentum is 2000 kg m/s. Substituting the values yields:

$F = \frac{2000 ext{ kg m/s}}{2.3 ext{ s}} \approx 870 \text{ N}$

Andrew is not injured during his fall primarily due to the relatively long impact time, which allows forces to be distributed over a longer period. Additionally, the force acting on him is not excessively high because his deceleration is gradual. Furthermore, the distance over which he slides reduces the rate of change of momentum, minimizing the impact force he experiences.