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A cyclist is riding a bicycle at a steady velocity of 12 m/s - Edexcel - GCSE Physics Combined Science - Question 6 - 2018 - Paper 1
Question 6
A cyclist is riding a bicycle at a steady velocity of 12 m/s. The cyclist and bicycle have a total mass of 68 kg. (a) Calculate the kinetic energy of the cyclist an... show full transcript
Worked Solution & Example Answer:A cyclist is riding a bicycle at a steady velocity of 12 m/s - Edexcel - GCSE Physics Combined Science - Question 6 - 2018 - Paper 1
Step 1
Calculate the kinetic energy of the cyclist and bicycle.
Answer
To find the kinetic energy (KE), we use the formula:
where: m = total mass = 68 kg, v = velocity = 12 m/s.
Substituting the values into the equation:
Hence, the kinetic energy of the cyclist and bicycle is approximately 4900 J.
Step 2
Describe the energy transfers that happen when the cyclist uses the brakes to stop.
Answer
When the cyclist uses the brakes, the kinetic energy of the cyclist and bicycle is reduced, which means the motion energy is transferred.
This energy is usually converted into heat energy due to friction between the brake pads and the wheels, causing the bicycle to decelerate. In summary, kinetic energy is transformed into thermal energy, leading to a stop.
Step 3
Calculate the average force the cyclist exerts.
Answer
To find the average force exerted by the cyclist, we can use the work-energy principle:
Given that the work done is 1600 J and the distance traveled is 28 m, we can rearrange the formula to solve for force:
Therefore, the average force the cyclist exerts is approximately 57 N.