A bicycle has pedal rods of length `16 cm` connected to sprocketed disc of radius `10 cm`. The bicycle wheels are `70 cm` in diameter and the chain runs over a gear of radius `4cm`. The speed of the cycle is constant and the cyclist applies `100 N` for, that is always perpendicular to the pedal rod, as shown in figure. Assume tension in the lower part of chain is negligible. The cyclist is peddling at a constant rate of two revolutions per second. Assume that the force applied by other foot is zero when one foot is exerting `100 N` force. Neglect friction within cycle parts and the rolling friction.

The power delivered by the cyclist is equal to

Options

A. `280W`
B. `100W`
C. `64piW`
D. `32W`

Answer

C

Explanation

Power delivered `=vecF.vecv`
where `vecv` is velocity of the point of application of the force.
`v=16cmxx2pi.2(=Romega)`
`=0.64pims^(-1)`
`P=100xx0.64pi=64piW`