Moments

The figure below shows a man lifting a heavy rock using a steel bar. He pushes downwards on the end of the bar with a force F.

Which pivot positions allows the force F to be as small as possible?

• A

• B

• C

• D

Explain why you choose the answer in Question 1.

A force is a applied to a long crowbar so as to move a large rock.

 Which labelled arrow represents the smallest force needed to move the rock?

• A

• B

• C

• D

Explain why you choose the answer in Question 3.

A boy of weight 600N sits on the see-saw as shown at a distance of 1.5m from the pivot. What is the force F required at the other end to balance the see-saw?

• 300 N

• 600 N

• 900 N

• 1200 N

Show detailed working on how you derived your answer for Quesion 5.

A wheelbarrow can pivot about point P. The weight of the wheelbarrow, W is 200 N.

Calculate the size of the force F that is required to keep the wheelbarrow in equilibrium.

• 50

• 66.7

• 200 N

• 600 N

Show detailed working on how you derived your answer for Quesion 5.

When a mug is placed on a tabletop, a force F is required to keep it horizontal. Assume that the force exerted by the mug on the tabletop is 7.0 N.

Calculate the size of force F, that is required to keep the table top horizontal.

• 1 N

• 1.75 N

• 7 N

• 17.5 N

Show detailed working on how you derived your answer for Quesion 5.