Q. The centre of mass of a system cannot change its state of motion, unless there is external force acting on it. Yet the internal force of the brakes can bring a car to rest. Then
A) The brakes stop the wheels
B) The friction between the brake pads and the wheel stop the car
C) The car is stopped by the road
D) The car is stopped by the driver pressing the pedal
Explanation
(c) The car is stopped by the contact force exerted due to road
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.