New
New
Year 11
AQA
Higher

Moments, levers and gears

I can explain how levers and gears transmit the rotational effects of forces.

New
New
Year 11
AQA
Higher

Moments, levers and gears

I can explain how levers and gears transmit the rotational effects of forces.

Lesson details

Key learning points

  1. A force can produce a turning effect known as a moment.
  2. If an object is in equilibrium, there is no resultant force or moment on it.
  3. moment = force × distance (M = Fd)
  4. Levers can act as force or distance multipliers.
  5. Gears can be used to transfer moments.

Common misconception

Pupils may think that a lever gives you ‘something for nothing’ when used as a force multiplier.

Ask a pupil to lift an object by a particular height (say 10 cm) without a pivot, then with a pivot and a plank as a lever to compare the effort and distance moved in each case.

Keywords

  • Equilibrium - The state of an object when there is no resultant force or moment acting on it.

  • Moment - The turning effect of a force, measured in newton metres (Nm).

  • Force multiplier - A type of lever that increases the size of an applied force.

  • Distance multiplier - A type of lever that increases the distance an applied force moves through.

  • Gears - Toothed wheels that rotate around an axle and are used to transfer moments.

Always refer to a moment as a ‘turning effect’, as a moment is not a force and is not measured in newtons. Model gears (e.g. Lego or Meccano) really help pupils to see how one gear can turn another; these should be used in demonstrations if available.
Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Which of the following are the unit of force and its symbol?
Correct answer: newtons
neutrons
n
Correct answer: N
Q2.
An object is __________ if no resultant force acts on it.
speeding up
Correct answer: in equilibrium
changing direction
decelerating
Q3.
What is the resultant force acting on the parachutist?
An image in a quiz
Correct answer: 200 N upwards
200 N downwards
1900 N upwards
1900 N downwards
Q4.
Which of the following conditions is required for an object to be in equilibrium?
There are no forces acting on the object.
There is an even number of forces acting on the object.
Correct answer: The vector sum of the forces acting on the object is zero.
The forces acting on the object are all in equal and opposite pairs.
Q5.
When an object rotates in the same direction as the hands on a clock, the direction of rotation is called .
Correct Answer: clockwise
Q6.
When an object rotates in the opposite direction as the hands on a clock, the direction of rotation is called .
Correct Answer: anticlockwise, anti-clockwise

6 Questions

Q1.
Match the following key terms to their definition.
Correct Answer:equilibrium,the state of an object if there is no resultant force or moment on it

the state of an object if there is no resultant force or moment on it

Correct Answer:moment,the turning effect of a force, measured in newton metres (Nm)

the turning effect of a force, measured in newton metres (Nm)

Correct Answer:force multiplier,a lever that increases the size of an applied force

a lever that increases the size of an applied force

Correct Answer:distance multiplier,a lever that increases the distance an applied force moves through

a lever that increases the distance an applied force moves through

Correct Answer:gear,a toothed wheel that rotates and is used to transfer a moment

a toothed wheel that rotates and is used to transfer a moment

Q2.
In how many of the following situations is the box in equilibrium?
An image in a quiz
Correct answer: 0
1
2
3
Q3.
A lever can be a force multiplier or a distance multiplier. Which of the following levers is a distance multiplier?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q4.
What is the moment about the pivot caused by the force in the following diagram?
An image in a quiz
40 Nm clockwise
40 Nm anticlockwise
1.6 Nm clockwise
Correct answer: 1.6 Nm anticlockwise
Q5.
What is the moment caused by the force about the pivot in the following diagram? You need to choose the correct distance for your calculation.
An image in a quiz
33 Nm
Correct answer: 39 Nm
54 Nm
58 Nm
Q6.
The diagram shows a set of gears, X and Y, in a machine. Using an attached handle, a person produces a moment of 18 Nm about gear X, which rotates once. Which of the following statements are correct?
An image in a quiz
Correct answer: Gear Y makes 3 rotations.
Gear Y makes $$\frac{1}{3}$$ of a rotation.
Correct answer: The moment of gear Y is Nm.
The moment of gear Y is 18 Nm.
The moment of gear Y is 36 Nm.