Moments

The moment of a force causes an object to

• move forward

• move backward

• stop moving

• turn about a fixed point

Moment can be calculated using the equation:

• M = F × d

• M = F / d

• M = F² × d

• M = F / d²

The SI unit of moment of force is –

• m

• N

• kgf

• Nm

When an object is in equilibrium, which equation is true?

• Clockwise moment = anticlockwise moment

• Clockwise moment + anticlockwise moment = 0

• Clockwise moment / anticlockwise moment = 0

• Clockwise moment + anticlockwise moment = resultant force

A nut can be loosen more easily with

• A short spanner because a large turning effect can be produced

• A short spanner because a larger force can be produced.

• A heavy spanner because a larger force can be produced.

• long spanner because a large turning effect can be produced.

The easiest way to open a heavy door  is by applying the force

• Near the hinges
• In the middle of the door
• At the edge of the door far from the hinges
• At the top of the door

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

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?

• 450 N

• 350 N

• 4.5 N

• 200 N

Which solid block remains at rest under the action of the forces shown?

• A

• B

• C

• D

why is the car on the right more stable?

• Its centre of mass is higher
• it has a wider base
• it has more height
• all of the above