A pair of cameras is used on a motorway to help determine the average speed of vehicles travelling between the two cameras - AQA - A-Level Physics - Question 4 - 2020 - Paper 1

To find out if the average speed of the car exceeded the speed limit, we first need to calculate the area under the speed-time graph given in Figure 5. The average speed can be determined using the formula:

$ext{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}}$

From the graph, calculate the area which represents the distance travelled:

1. Calculate the area under the sections of the graph: trapezoids and rectangles could be used here.
2. Assume the following area calculations based on the graph segments:
   • For the first segment (0 to 1 minute), calculate the area as a triangle or rectangle.
   • For the following segments, use similar methods.
3. Sum the areas to find the total distance travelled by the car in meters.
4. The total time taken is 4 minutes, which is equivalent to 240 seconds.

Finally, calculate the average speed and compare it to the speed limit of 22 m s⁻¹. If the calculated average speed exceeds this limit, it confirms that the car exceeded the speed limit.