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1 (a) The work done to bring a car to rest is given by the equation work done = braking force × braking distance Which of these graphs is correct for the car if a constant braking force is applied? (Refer to Figure A, B, C, D) (b) Before the car brakes it has kinetic energy - Edexcel - GCSE Physics - Question 1 - 2019 - Paper 1
Question 1
1 (a) The work done to bring a car to rest is given by the equation work done = braking force × braking distance Which of these graphs is correct for the car if a ... show full transcript
Worked Solution & Example Answer:1 (a) The work done to bring a car to rest is given by the equation work done = braking force × braking distance Which of these graphs is correct for the car if a constant braking force is applied? (Refer to Figure A, B, C, D) (b) Before the car brakes it has kinetic energy - Edexcel - GCSE Physics - Question 1 - 2019 - Paper 1
Step 1
Which of these graphs is correct for the car if a constant braking force is applied?
Answer
A car decelerating due to a constant braking force will have a work done that increases as the braking distance increases. Therefore, the correct answer is graph A, where the work done increases linearly with the braking distance. This is consistent with the equation:
Since the braking force is constant, the relationship should be linear.
Step 2
State what happens to the kinetic energy during braking.
Answer
During braking, the kinetic energy of the car decreases. As the brakes are applied and the braking force acts against the motion of the car, the car's speed reduces, leading to a decrease in kinetic energy. The work done by the brakes is equal to the loss of kinetic energy of the car, which is converted into heat. Thus:
The kinetic energy continues to decrease until the car comes to a stop.