How Is Upward Force Calculated in a Lever System?

[Liamsbab]

Homework Statement

The thigh muscle that bends the knee is attached to the bone 2cm away from the fulcrum and generates a force of 400N. The distance between the weight and the fulcrum is 40cm. Calculate the upward force at the point where the muscle in the thigh contracts.

Homework Equations

No idea, i am really confused.

The Attempt at a Solution

None

 

[berkeman]

What can you tell us about torques? Can you sketch a diagram showing the problem statement, and label the forces, where they act, and how they make torques?