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A car is moving at a speed of 72 km//h. ...

A car is moving at a speed of `72 km//h`. The diameter of its wheels is `0.5 m`. If the wheels are stopped in `20` rotations by applying brakes, calcualte the angular retardation produced by the brakes.

A

`-25.5 "rad"//s^(2)`

B

`-29.5 "rad"//s^(2)`

C

`-33.5 "rad"//s^(2)`

D

`-45.5 "rad"//s^(2)`

Text Solution

Verified by Experts

The correct Answer is:
A
`v= 72 xx (5)/(18)= 20 m//s, omega_(0) = (v)/(r)= (20)/(0.25)= 80` rad/sec
`theta= 2pi xx 20= 40pi` rad
`omega^(2)= omega_(0)^(2) + 2 alpha theta`
`rArr alpha= - ((80)^(2))/(2 xx 40 pi)= (-80)/(pi)= -25.5` rad/sec
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