Which of the following statements about friction is NOT correct?
A
The force of kinetic friction is less than the force of static friction
B
The force of kinetic friction between two surfaces is independent of the areas in contact provided the normal reaction is unchanged
C
The force of rolling friction between two surfaces is less than the force of sliding friction
D
The angle of friction is the angle between the normal reaction and the force of friction
E
Friction may be reduced by lubrication
Verified Correct Answer: D.
Physical Principles & Numerical Solution
- Static Friction is friction which is experienced when an object is placed on a surface. And, Kinetic friction is due to the movement of an object on a surface.
- Static friction is greater than kinetic friction because there are more forces at work keeping an object stationary than there are forces working to resist an object once it is in motion.
- Rolling friction is the weakest type of friction, static being the strongest. The frictional force depends on the area of contact between the two bodies. As the area of contact is less in rolling friction than the sliding friction, so rolling friction is weaker than sliding friction.
Source: Myschool Past Questions Archive (Record #28762)