(i) Tension in a string:

“the force exerted by a string when it is subjected to pull is called tension in the string”

If a person is holding a block of weight W attached to the end of a string, a force is experienced by him. This force is known as Tension. When the body is at rest, the magnitude of tension is equal to the weight of the body suspended by the string Tension and the weight acts in the opposite direction.

Unit of tension:                                                                           

In S.I. system: newton

In C.G.S. system: dyne

In the F.P.S. system: the pound

(ii) Braking force:

Friction between a rotating component (the drum or disc) and a stationary force is called braking force.

1. The diameter of the disc
2. The friction material
3. The size of the pad friction face
4. The force used to clamp the pads onto the disc
5. The greater the diameter of the disc, the further from the centre of the wheel the braking force can be applied. This, in turn, will generate a greater force, or torque, on the disc.

(iii) Seatbelts:

In case of an accident, a person not wearing a seatbelt will continue moving until stopped by something before him, This something may be a windscreen another passenger or the back of the seat in front of him/her. Seatbelts are useful in two ways.

1. They provide an external force to a person wearing a seatbelt.
2. additional time is required for stretching seatbelts. This prolongs the stopping time for momentum to change and reduces the effect of collision.

(iv) Banking of roads:

The curvature of the road must be inclined to control the Centrifugal force of the Vehicle.

Banking of road means to make the road slide towards the centre of curvature with an angle. It is helpful because the velocity of the car is more or there is less friction between the tyres and the road which reduces the danger of the car moving out of the circular track. 

Explanation:

When a car takes a turn, the centripetal force is needed to keep it on its curved track. The friction between the tyres and the road provides the necessary centripetal force. The car would skid if the force of friction between the tyres and the road is not sufficient enough particularly when the roads are wet. This problem is solved by the banking of curved roads.

(v) Cream separator:                

Most modern plants use a separator to control the fact contents of various products. A separator is a high-speed spinner. It acts on the same principle as centrifuge machines. The bowl spins at a very high speed causing the heavier contents of milk to move outward in the bowl pushing the lighter contents inward towards the spinning axis

Cream or butterfat is lighter than other components in milk. Therefore, skim milk, which is denser than cream is collected at the outer wall of the bowl. The lighter part (cream) is pushed towards the centre from where it is collected through a pipe.