# Homework Help: Lever physics homework

1. Dec 8, 2006

### Kogsug

I cant figure this problem out and i dont know where to start.

A young boy(50kg) wants to lift a boulder with a mass of 2500kg. He can wedge a board under it so that from the boulder to a pivot/fulcrum is 0.6 meters. How long does the other end of the board have to be for the boy to lift the boulder.

Any ideas?

2. Dec 8, 2006

### Staff: Mentor

What principles apply here? (See, this is why you should use the Homework Posting Template that is provided when you start a new homework thread. It should not be considered optional.)

Tell us what you know about levers and fulcrums and maybe even torques. You must show us your work in order to get our help (PF rules).

3. Dec 8, 2006

### Ja4Coltrane

does it make sense that if you set the persons torque equal to the boulder's torque you would be able to solve this problem?

4. Dec 10, 2006

### Kogsug

what do u mean what principles apply here? this is the full problem word for word. we just started levers... and we have not done torgue.

does this work?

(50kg)(x)=(0.6m)(2500kg)

x={(0.6m)(2500kg)}/(50kg)

so x=30 meters?

can somone please tell me if this is right?

Last edited: Dec 10, 2006
5. Dec 10, 2006

### Staff: Mentor

Looks good to me.

6. Dec 11, 2006

### Kogsug

ok then... thank you