IGCSE Physics

Work and Power

• Work is done when a force causes an object to move in the direction of the force.
• Power is the rate at which energy is transferred.

Transfer of Energy

The student in the picture below is having  a lot of fun. Isn’t she?

But she is doing work, even though she is having fun.  She is doing work

because she is applying a force to the bowling ball and making the ball

move through a distance.  One way you can tell she has done work on the

bowling ball is that the ball now has kinetic energy.  This means that the ball

is now moving. The bowler has transfered energy to the ball.

 

How Much Work?
Would you do more work pushing a box up a ramp to the back of a truck or
lifting the box to the back of the truck?
You may bw supprised to learn that the same amount of work is being done.

                                  W = F x d

Force 1 (F1) is a greater force than force 2 (F2). However distance 1 (d1)
is less than distance 2 (d2). The work is the same.

Force:
Force is expressed in newtons, andf the miter is the basic SI unit forlength or distence.

Joule:
Joule is the unit used to measure energy.

Power:
Power is the rate at which energy is transferred.

Watt:
Watt is the unit used to express power; equlivantto joules per second (symbob, W)

Calculating Power:
Powet (P) is calculated by dividing the amount of work being done by the time (t) it takes to do the work.

                                  P = W / t