4.3 Turning effect of forces [mastery check]

A nut can be loosened more easily with

• a short spanner because a larger turning effect can be produced.

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

• a long spanner because a larger force can be produced.

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

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 anticlockwise moment acting on this crane?

• 80,000Nm
• 100,000Nm
• 120,000Nm
• 140,000Nm

A seesaw is unbalanced with two people of different masses sitting equal distances from the center. Which of the following will result in equilibrium?

• The larger person moving further away from the center.
• Moving the smaller person closer to the center.
• Moving the smaller person further from the center.
• Making the larger person do nothing.

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

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

• 3.4 m

• 2.8 m

• 4.4 m

• 1.6 m

What is the equation for moments?

• Moment = force x perpendicular distance from pivot

• Moment = mass x velocity

• Moment = force x distance

• Moment = force x parallel distance from pivot

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

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

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