Question

A car is moving at a speed of 72 km/hr the radius of its wheel is 0.25m. If the wheels are stopped in 20 rotations after applying breaks then angular retardation produced by the breaks is ……

(A) – 25.5 rad/s2

(B) – 29.5 2 rad/s2

(C) – 33.5 2 rad/s2

(D) – 45.5 2 rad/s2

Answer 1

Correct option: (A) – 25.5 rad/s2

Explanation:

Given:

r = 0.25m

V = 72 kmph = [(72 × 1000) / (3600)] = 20 m/*

as V = rω hence ω0 = (v/r) = [(20) / (0.25)] = 80rad/*.

θ = 2πN = 2π × 20 = 40π rad.

2 ∝ θ = w2 – w02

∝ = [(w2 – w02) / (2θ)] = [(02 – 802) / (2 × 40π)]

= – 25.46 rad/s2