Question

Which of the following is used to reduce friction:
1. Streamlines
2. Use of ball bearings
3. Lubrication
(A) 1 and 2 only
(B) 1 and 3 only
(C) 2 and 3 only
(D) 1, 2 and 3

Answer 1

Hint :Friction can be defined as the resistance which one surface or the object encounters when moved one over the other. To get the answer and to complete the given statement, refer all the given terms in the multiple-choice options and then will find out the correct option. Know the difference and its applicable properties.

Complete Step By Step Answer:
Streamlines: Streamlines can be defined as the design or the pattern with the form which presents very little resistance to flow of air or water which increases the speed and the ease of the movement. It is easiest and the path traced out by the massless particle as it moves with the flow and it reduces the friction in the fluid.
Ball bearings: Ball bearing can be defined as the type of the rolling element which uses the balls to maintain the separation between the bearing spaces. The purpose of the ball bearing is to reduce the friction of the rotating parts in the machines.
Lubricants: The lubricant can be defined as the substance which was introduced to reduce the friction between the surfaces in the mutual contact and also reduces the heat generated. It is used in machines and the other moving parts which reduces the friction.
Hence, from the given multiple choices- the option D is the correct answer.

Note :
Know the properties of different substances or the material which reduces the friction and the resistivity. The resistivity is the property which resists or opposes, here it opposes the motion or speed.