Photo AI
The distance a car travels during the driver’s reaction time is called the thinking distance - AQA - GCSE Physics Combined Science - Question 6 - 2022 - Paper 2
Question 6
The distance a car travels during the driver’s reaction time is called the thinking distance. Figure 9 shows how thinking distance depends on speed for a car. Dete... show full transcript
Worked Solution & Example Answer:The distance a car travels during the driver’s reaction time is called the thinking distance - AQA - GCSE Physics Combined Science - Question 6 - 2022 - Paper 2
Step 1
Determine the driver’s reaction time.
Answer
To determine the driver's reaction time, we can use the relationship between thinking distance and speed. From Figure 9, we see that at a speed of 30 m/s, the thinking distance is 21 m. Using the equation:
We can rearrange for reaction time:
Thus, the driver's reaction time is 0.7 seconds.
Step 2
Determine the braking distance of the car.
Answer
To find the braking distance, we first need to interpret Figure 10. Each square on the graph represents 5 meters. Counting the number of squares for the braking distance: there are approximately 9 squares covered during the braking phase. Therefore:
Thus, the braking distance of the car is 45 meters.
Step 3
Explain how the gradient of the line on Figure 10 shows that the resultant force on the car was not constant.
Answer
The gradient of the line on Figure 10 is proportional to the acceleration of the car. As the car brakes, the gradient (acceleration) decreases, indicating that the car is slowing down at a changing rate. Since force is directly proportional to acceleration (F = ma), this means the resultant force acting on the car is also not constant. Therefore, as the car decelerates, the changing gradient signifies that the resultant force is not constant throughout the braking process.