Question

What is work done? Write the different types of work with
examples.​

Answer 1

Answer:

Positive, Negative and Zero work done - definition

Positive Work : If a force displaces the object in its direction, then the work done is positive. The example of this kind of work done is motion of ball falling towards ground where displacement of ball is in the direction of force of gravity. 2.

Explanation:

hope this helps you

Answer 2

Answer:

• Work Done and Energy. To move an object, it should be transferred to energy. Transferring energy can be in the method of force. This quantity of energy transferred by the force to move an object is termed as work done.

• W = F.S or W = F S cosq …(1)  

where F = force and S = displacement

And q = angle between F and S.

From eq.(1), we have W=F cosq x S. Therefore, work done by a force is equal to the product of the component of the force in the direction of displacement of the body and the distance through which the body moves.

As work is the dot or scalar product of two vectors (force and displacement), therefore, it is a scalar quantity.

Special cases:

CaseI: When the body moves in the direction of the force. In this case, q = 0o.

from eq (i), we have

W = FScosoo

i.e. W = FS …(ii)

i.e. W = product of the force and the distance through which the body moves in the direction of the force.

This type of work is said to be positive. Therefore, work done by a force is positive is q < 90o

• EXAMPLES

1. When a spring is stretched, the work done by the stretching force is positive as the force acts in the direction of displacement of the spring.
2. When a body falls freely under gravity, the work done by gravity is positive as force (gravity) and displacement of the body are in the same direction.