Work

Definition:-

"Work is the product of force and the distance covered by a body due to force applied on it"

Explanation:-

In physics work is done on a body, when we apply some force on it and it covers some distance in the direction of force.

Work is not done until body is not covering some distance whether force is applied on it or not, body has to cover some distance in order to get work done. or work will not be done until force will not be apply on it whether it is covering some distance or not. so both things are necessary.

Example:-

1.When you try to push the box by applying force on it and box start to move in direction of force, then your are doing work.

2.When you try to push the wall then you apply force but wall doesn't move, so you are not working (According to physics).

Unit:-

The Sl unit of work is joule J

Formula:-

Work also have an formula to calculate it mathematically,

W=F.d.cosθ

As define work is the product of force and distance and the angle between them. 

Conditions:-

1.This cos shows that when force applied and distance covered is in same direction then angle will be 0, where cos(0)=1, hence work will be maximum.

2. When force applied and distance cover will be perpendicular to each other than angle will be 90 and cos(90)=0, hence work will be 0.

3. When force applied and distance covered is in opposite direction  then work will be negative as, angle will be 180 and cos(180)=  -1.

Centripetal force

Definition:

"Centripetal force is a force, which keeps a body moving in a circular path and that force acting towards the center of that circular path."

Explanation:

A body never automatically or itself moves in a circular path it, there is always a reason or some force that causes it to move in a circular path and that force in general is known as a centripetal force. and that force is always directed towards  center. it means force is from the center of circular path that causes it to move in a circular path.

Example:

You tries to move a string in a circular path. one end of it is in your hand and other is tied with a stone. and consider that stone is a body. you provide force from your hand which is at the center of circular path in which stone(body) is moving.

Formula:

 

This equation shows that force depends on the mass of body and the velocity by which it is moving in path and the distance(r) between the center of circular path and body.

What is Force?

Definition:-

"Force is a reason or something that causes the change in a motion or situation of a body."

Explanation:

Force is the reason which causes change, if you want to move something or you want to do some work you have to apply force.
A force is a vector quantity. a vector quantity is a quantity that has both magnitude and direction.




Unit:

Force is a quantity that is measured using the standard metric unit known as the Newton.  
1 Newton = 1 kg • m/s2

Formula:

According to the newton second law of motion, force is the product of mass and acceleration. Means force depends on mass and acceleration of body.It means that if a body has change in its velocity(speed) or position, then its depend upon the total force acting upon him and the mass of the body. It is also known as law of inertia. Having low mass will demand less force for change in its speed.
F=m.a