Work & Power

A cat tries to climb up onto a ledge In the process, she has to fight her own weight, 98.1 N. If the ledge is 3 m off the ground, how much work doe she do?

Her weight is the force she has to overcome, so F = 98.1 N

She climbs a distance of 3 m, so d = 3 m

Our equation is W = F x d

so... W = 98.1 x 3 = 294.3 J

Work is a form of USEFUL energy.

If there is no force or no distance, there can be no work done.

Also, don't forget it's always measured in Joules, J.

This means that if you can do MORE work in a small amount of time, you are MORE powerful.

Power is not strength, it has nothing to do with muscle or anything, but rather speed.

Power is measured in Watts, W.

How much power is used when 9000 J of work are done in 0.5 seconds?

So we have 9000 J of work, W = 9000 J

We have a time of 0.5 seconds, so t = 0.5 s

Our equation is  $P=\frac{W}{t}$  

thus...   $P=\frac{9000}{0.5}$  

P = 18,000 W      (the W stands for watts, not work)