Question

What is work ? Define work by giving examples also write all the situations when work done is zero with examples.

Answer 1

$\huge\underline\blue{\sf Answer:}$

$\large\underline{\underline{\sf Work:}}$

Whenever a force acting on a body , displaces it in its direction , work is said to be done by the force . Work done by a force is equal to scalar product of force applied and Displacement of the point of application .

$\large{→}$ Work is scalar quantity.

Work (W) = F.ds

Or

$\large{\sf W=Fscos\theta }$

$\large\underline{\underline{\sf Example\:of\:Work:}}$

• Work done by braking force on the car.

• Work done by friction force.

• When a body falls under the action of gravity .

$\large\underline{\underline{\sf Example\:when\:Work\:done\:is\:zero:}}$

$\large{\boxed{\sf W=Fs cos\theta}}$

Work done will be Zero if :-

• F = 0

• s = 0

• $\theta$ = 90°

Example :-

• Body is moving with uniform Velocity . Work done by net force=0

Net force on the particle is zero then work done on the body is also zero

• When we push the wall and it remains at rest , their work done is zero.

• Work done by Coolie against gravity is zero.

• When satellite is moving around the earth work done by gravitational force is zero.

• When Electron is moving around the nucleus Work done by attractive force is zero.

• When a pendulum is oscillating the work done by tension is zero.