My Scratch

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

Assuming the system is in equilibrium, calculate the missing distance d

• 3.4 m

• 2.8 m

• 4.4 m

• 1.6 m

The diagram shows a beam. Without any weights, the beam balances at its centre.

Three weights are hung as shown.

At which point does a load of 2 N balance the beam?

• A

• B

• C

• D

What is the size of the moment shown by the black arrow?

• 30 Nm

• 36 Nm

• 40 Nm

• 60 Nm

What is the moment produced by the 15 N?

• 15 Nm (clockwise)
• 150 Nm (anti - clockwise)
• 1.5 Nm (anti - clockwise)
• 0.15 Nm (clockwise)

The turning effect of a force on a door is greater when it is applied at

• A point near the hinges and perpendicular to the door

• A point near the hinges and parallel to the door

• A point far away from the hinges and perpendicular to the door

• A point far away from the hinges and parallel to the door

Jack has a weight of 300 N and sits 2.0 m from the pivot of see-saw. Jill has a weight of 450 N and sits 1.5 m from pivot. Who will move down?

• Jack

• Jill

• Both of them

• None of them

What is the force F needed to balance the bar shown?

• 3

• 4

• 6

• 8

A light metre rule is allowed to pivot freely at the zero end. The other end is supported by a spring balance. A weight of 200N is then hung at the 40cm mark. The metre rule stays horizontal. What is the reading on the spring balance?

• 80

• 40

• 8

• 4

A nut has been tightened by a force of 180 N using 8 cm long spanner. What length of a spanner is required to loosen the same nut with 150 N force

• 11 cm

• 8.5 cm

• 9.6 cm

• 10.9 cm