An automobile moves on a road with a speed of 54 km h-1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is :
8.58 kg m2 s-2
10.86 kg m2 s-2
2.86 kg m2 s-2
6.66 kg m2 s-2
As we learned in concept
Analogue of second law of motion for pure rotation -
- wherein
Torque equation can be applied only about two point
(i) centre of motion.
(ii) point which has zero velocity/acceleration.
V=54 Km/hr = 15m/s
Angular velocity of vehicle V=W0r
Angular Accn
=>
Option 1)
8.58 kg m2 s-2
This option is incorrect.
Option 2)
10.86 kg m2 s-2
This option is incorrect.
Option 3)
2.86 kg m2 s-2
This option is incorrect.
Option 4)
6.66 kg m2 s-2
This option is correct.