In which of the following situations is friction not useful?
A
Operation of a grinding machine
B
Walking
C
Application of brakes
D
Moving piston in a sleeve
Verified Correct Answer: D.
Physical Principles & Numerical Solution
friction, force that resists the sliding or rolling of one solid object over another.
Examples of friction in our daily life
Driving of a a vehicle on a surface.
Applying brakes to stop a moving vehicle.
Skating.
Walking on the road.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63420)