A car is moving at a speed of 72 km/hr. The radius of its wheels is 0.25m. If the wheels are stopped in 20 rotation by applying brakes, then angular retardation produced by the brakes is:

Answer 1

Circumference = pi*2r = 3.14 * 0.5 = 1.57 m.

Vo = 72,000m/3600s * 6.28rad/1.57m = 80 rad/s.

d = 20rev * 6.28rad/rev = 125.6 rad.

V^2 = Vo^2 + 2a*d.
V = 0, Vo = 80 rad/s, d = 125.6 rad, a = ?. "a" will be negative.

Answer 2

Car is moving at a speed of 72 km/hr. The diameter of its wheel is 0.5 m if the wheels are stopped in 20 rotations applying breaks , then angular retardation produced by the break would be *