## Engineering Mechanics Which of the following statement is incorrect?

The velocity ratio of a machine is the ratio of load lifted to the effort applied
A machine whose efficiency is 100% is known as an ideal machine
A force acting in the opposite direction to the motion of the body is called force of friction
The ratio of the limiting friction to the normal reaction is called coefficient of friction

## Engineering Mechanics The coefficient of friction depends upon

Shape of the surfaces
All of these
Area of contact
Nature of surfaces

## Engineering Mechanics A machine having an efficiency less than 50%, is known as

Neither reversible nor non-reversible machine
Reversible machine
Non-reversible machine
Ideal machine

## Engineering Mechanics The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction in which the force acts. This statement is known as

Newton's second law of motion
Newton's first law of motion
None of these
Newton's third law of motion

m/s2