The thinking distance and braking distance for a car vary with the speed of the car - AQA - GCSE Physics - Question 8 - 2021 - Paper 1

The correct equation is:

resultant force = mass × acceleration.

Given

Mean braking force, $F = 7200 \, N$
Mass, $m = 1600 \, kg$

Using the formula: $F = m imes a$
We can rearrange to find acceleration (deceleration in this case): $a = \frac{F}{m} = \frac{7200}{1600} = 4.5 \, m/s^2$

Thus, the deceleration of the car is $4.5 \, m/s^2$.

From Figure 18, at a speed of 80 km/h, the stopping distance is indicated to be 53 meters.

The correct equation is:

p = \frac{F}{A}.

We know:
Pressure, $p = 120000 \, Pa$
Force, $F = 60 \, N$
Using the formula: $p = \frac{F}{A}$
Rearranging gives: $A = \frac{F}{p} = \frac{60}{120000} = 0.0005 \, m^2$

In standard form, this is: $A = 5.0 \times 10^{-4} \, m^2$

The unit is $m^2$.