Question

Q5.Suggest how one can reduce friction in the following cases: a) in motors and dynamos ​

Answer 1

Answer:

both (a) and (b) part have the same answer. hope it helps you to understand..

1. POLISHING : When we Polish a surface, it's roughness decreases. The surface becomes smooth and friction gets reduced. We also sometimes rub the surface with a fine sand paper to reduce their unevenness.

2. LUBRICATION : We all know that when a few drops of oil are poured on the hinges of a door, the door moves much more smoothly. Bicycle and motor mechanics use grease between the moving parts of these machines. In all these cases, we want to reduce friction in order to increase efficiency. Oil-like substances, which help to reduce friction when put on a surface, are called lubricants. Lubricants can be liquid, semi liquid, solids.

3.BALL-BEARING: We know that rolling friction is smaller than sliding friction. Sliding can be replaced by rolling , by use of ball bearing so. For example, we use ball bearings in shafts of motors, dynamos, axles of vehicles and so on.

Answer 2

Ways to reduce friction in motors and dynamos :

1. Lubrication :

• Lubrication is the oldest and most efficient way to reduce friction among the moving parts of a motor.

• Lubrication reduces the wear and tear between the contact surfaces of the machines.

• This also improves the efficiency of the machine.

2. Polishing :

• Polishing helps to remove the undulations in the surfaces that are in contact with one another.

• This reduces friction.

3. Use of Ball Bearings:

• Use of ball-bearings is based on the principle : ROLLING FRICTION IS LESSER THAN SLIDING FRICTION

$\star$ Hope It Helps