The velocity of a car travelling on a straight road is 36 km `h^(- 1)` at an instant of time. Now travelling with uniform acceleration for 10s, the velocity becomes exactly double. If the wheel radius of the car is 25 cm, then which of the following numbers is the closest to the number of revolutions that the wheel makes during this 10 s?

Options

A. 84
B. 95
C. 126
D. 135

Answer

B

Explanation

Angle rotated before corning to rest.
`theta=(((V_(f)^(2))/(r^(2))-(v_(i)^(2))/(r^(2))))/(((2a)/r))=(v_(f)^(2)-v_(i)^(2))/((2ar))`
`therefore` Number of rotation,
`n=(theta)/(2pi)=(v_(f)^(2)-v_(i)^(2))/((2ar)(2pi))=95`