Friction is a type of:
contact force.
non contact force.
resistance force.
motion.
Powder is used in carrom board for
Increasing friction.
Decreasing friction.
Decoration.
Fragrance.
Which of the following activities is easier to perform?
Dragging a box.
Lifting a box.
Rolling a drum of same weight.
All of the above need same effort.
Which of the following material is likely to have least friction?
Wood.
Plastic.
Glass.
Paper.
Which of the following statements is NOT true?
Friction can be reduced by converting sliding friction into rolling friction.
Friction in air and water can be reduced by streamlining the shape of the object.
A polished surface will have less friction.
Friction can be reduced to zero.
Friction reduces efficiency of machines due to
Production of heat.
Wearing out of moving parts.
Increase in energy consumption.
All of the above.
The application of decreasing friction include
I. Ball bearing used in moving parts of a machine.
II. The streamlined shape of an aircraft.
III. The layer of air between the hull of a hovecraft and the ground.
I and II only
II and III only
III and I only
All of these
When a body is sliding over other body with a constant speed, the force of friction acting on it is
Static friction.
Limiting friction.
Dynamic friction.
Rolling friction.
The magnitude of a frictional force depends on
I. The surface area of contact.
II. The weight of the object.
III. The condition of the surface in contact.
Which of the following is not a method used for reducing friction
Use of lubricant.
Polishing the surfaces.
Streamlining.
Making the surface rough..