Question

The substance that helps to ___________ friction is called lubricants.
(A). increase
(B). decrease
(C). create
(D). eliminate

Answer 1

Hint: Friction is the force acting between two surfaces in contact with each other. It provides resistance to movement between the surfaces due to irregularities which naturally exist on every object. Friction has both advantages and disadvantages. It also has many applications in our day to day life.

Complete answer:
 The force which opposes the motion of an object is called friction. It exists due to irregularities in the surfaces. Friction is of different types- static, rolling, sliding.
Friction needs to be reduced because it causes wear and tear in machine parts, deformation of surfaces and energy is wasted as it is dissipated in the form of heat.
One way to reduce friction is to make the surfaces smoother; this decreases the unevenness of surfaces and reduces friction. Smoothening of surfaces can be done by polishing or using lubricants.
Lubricants are usually organic, slippery substances used for making the surfaces smooth and reduce friction.

Since lubricants make surfaces smooth and decrease friction, the correct option is (B).

Additional Information:
Static friction is the friction acting on an object at rest, rolling friction acts on an object rolling over another surface, sliding friction acts between surfaces sliding over each other.

Note:
Other ways of reducing friction are streamlining the bodies to reduce friction in fluids, known as drag, reduce forces acting on surfaces or to make the surfaces such that there is least contact between them. One way to do it is to make surfaces spherical in shape as a sphere has the least surface area.