During a collision between a bumper car and the barrier, the bumper car and barrier act as a closed system - AQA - GCSE Physics - Question 5 - 2023 - Paper 2

Newton's Third Law states that for every action, there is an equal and opposite reaction. In the collision, the force exerted by the bumper car on the barrier is met with an equal force exerted by the barrier on the bumper car, but in the opposite direction.

To calculate the force, we use the formula:

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

where Δp is the change in momentum (700 kg m/s) and Δt is the time (0.28 s).

Thus,

$F = \frac{700}{0.28} = 2500 \, N$.

The flexible bumper increases the time taken for the collision to occur, which reduces the rate of change of momentum. This decrease in acceleration or deceleration reduces the overall impact force experienced by the occupants, thus lowering the risk of injury.

We can use the kinematic equation:

$v^2 = u^2 + 2as$

Where:

• v = final velocity = 2.5 m/s
• a = acceleration = 2.0 m/s²
• s = distance = 1.5 m

Rearranging the formula to find u (initial velocity):

$u^2 = v^2 - 2as$ $u^2 = (2.5^2) - 2(2)(1.5)$ $u^2 = 6.25 - 6 = 0.25$ $u = 0.5 \, m/s$.