New
New
Year 11
AQA
Higher

Forces in two dimensions (including resolution of a force)

I can draw and interpret free body force diagrams to describe the resultant force on an object and resolve a force into perpendicular components.

New
New
Year 11
AQA
Higher

Forces in two dimensions (including resolution of a force)

I can draw and interpret free body force diagrams to describe the resultant force on an object and resolve a force into perpendicular components.

Lesson details

Key learning points

  1. A free body diagram shows all of the forces acting on a single object
  2. The resultant of two forces can be determined by adding individual forces on a vector diagram
  3. The resultant of two perpendicular forces is in a different direction from either of these forces
  4. A single force can be resolved into two components acting at right angles to each other
  5. The two component forces together have the same effect as the single force

Common misconception

The velocity of an object must be in the same direction as the resultant force acting on the object.

Invite pupils to consider situations in which the resultant force is not in the same direction as the velocity, such as an object that has been thrown upwards and is slowing down as its height increases.

Keywords

  • Resultant force - is a single force that represents the effect of all the forces on an object.

  • Equilibrium - is the state of an object if there is no resultant force acting on it.

  • Vector diagram - is a drawing on which forces are drawn end to end and to scale, which can be used to find a resultant force.

  • Component of a force - is one of two perpendicular forces that add up to a single force.

  • Resolving forces - splits a force into two perpendicular forces that add up to that force.

Pupils should use 1 cm squared paper to draw a range of forces to find a resultant, trigonometric techniques are not required. However, a parallelogram of forces technique can be used instead of 'joining forces end to end' if that is preferred.
Teacher tip

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.
How many newtons (N) are there in 53 kN?
5300 N
Correct answer: 53 000 N
530 000 N
53 000 000 N
Q2.
The diagram shows a force arrow drawn on a grid of 1 cm squares. What is the magnitude of the force?
An image in a quiz
left
right
3 N
6 N
Correct answer: 12 N
Q3.
There is a law of physics which states that an object will remain at rest, or in motion in a straight line at constant speed, unless a resultant force is acting on it. What is the name of this law?
Correct answer: Newton’s First Law of motion
Newton’s Second Law of motion
Newton’s Third Law of motion
Newton’s Fourth Law of motion
Q4.
What is the magnitude of the resultant force in this diagram?
An image in a quiz
Correct answer: 203 N
248 N
253 N
293 N
Q5.
The diagram shows an object with a single force acting on it. Which of the following are possible descriptions of the object’s motion?
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The object is moving to the left at constant speed.
The object is moving to the right at constant speed.
Correct answer: The object is accelerating.
Correct answer: The object is decelerating.
Q6.
A child throws a ball straight up. Which of the following is a correct free body diagram of the ball as it travels upwards?
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz

6 Questions

Q1.
A helicopter is in the air in a state of equilibrium. Which of the following motions are possible?
Correct answer: It is moving upwards at constant speed.
It is falling with decreasing speed.
It is travelling in a circle.
Correct answer: It is stationary.
Q2.
A duck is swimming in a straight line across the surface of a lake at a steady speed. Which of the following free body diagrams correctly shows the forces acting on the duck?
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q3.
An aeroplane and its free body diagram are shown. Which of the following are possible descriptions of the aeroplane’s motion?
An image in a quiz
Correct answer: Moving to the left at decreasing speed.
Moving downwards at increasing speed.
Moving up at increasing speed, while also moving steadily to the right.
Correct answer: Moving to the left at decreasing speed, while also moving steadily upwards.
Correct answer: Moving to the left at decreasing speed, while also moving steadily downwards.
Q4.
A spaceship in space uses two rockets to produce forces acting in two directions at the same time. Which of the following vector diagram shows how to find the resultant force?
An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q5.
The vector diagram shows the addition of three forces to find the resultant force. What is the magnitude of the resultant force?
An image in a quiz
Correct answer: 40 N
60 N
63 N
72 N
Q6.
The vector diagram shows a force on a grid of 1 cm squares. Which of the following is the correct description of the horizontal component of the force?
An image in a quiz
30 N upwards
30 N downwards
40 N to the right
Correct answer: 40 N to the left
50 N upwards and to the left