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The diagram shows a cyclist moving down ...

The diagram shows a cyclist moving down a small hill at P before travelling on a flat road after point Q. The total mass of the cyclist and his bicycle is 60 kg and the speed of the cyclist at P is 10 m `s^(-1)`. Which of the following is incorrect?
(Take acceleration due to gravity, g = 10 m `s^(-2)`)

A

The kinetic energy at P is 3000 J.

B

The loss of gravitational energy between P and Q is 1800 J.

C

Total energy is 4800 J.

D

The cyclist does not require a greater power when he travels at a higher constant speed.

Text Solution

Verified by Experts

The correct Answer is:
D
(A) `K=(1)/(2) xx 60 xx 10xx10=3000J`
(B) `PE=60 xx 10xx3=1800J`
(C ) Total energy = KE + Loss of gravitational potential energy = 3000 + 1800 = 4800 J
(D) When he travels at a higher constant speed, so a higher rate of work is done against air resistance.
`:.` Higher power is required.
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