# How much work would it take to push a # 5 kg # weight up a # 15 m # plane that is at an incline of # pi / 4 #?

##### 1 Answer

The work used to push the weight up the incline is converted into gravitational potential energy (P.E.). When the weight is at the top of the incline its P.E. is equal to the amount of work it took to get it up there. Therefore use P.E. = (mass) x (acceleration due to gravity) x (height of weight) = work done.

#### Explanation:

The work used to push the weight up the incline is converted into gravitational potential energy (P.E.). When the weight is at the top of the incline its P.E. is equal to the amount of work it took to get it up there. Therefore use P.E. = (mass) x (acceleration due to gravity) x (height of weight) = work done.

Use either Pythagoras' theorem

so,

Note that it's preferable to put the surd (the sqrt) in the numerator (the top part of the fraction):

Now taking:

plane length = 15m,

therefore:

acceleration due to gravity is approximately

and

mass = 5kg

Put these values into:

P.E. = (mass) x (acceleration due to gravity) x (height of weight) = work done

and you will find:

work done = 375

which is approximately 530 J.