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Year 8

Newton's First Law

I can describe and explain how a resultant force can change the movement of objects.

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New
New
Year 8

Newton's First Law

I can describe and explain how a resultant force can change the movement of objects.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Resultant forces make the movement of things change.
  2. Friction acts against the direction of movement of an object.
  3. An object will continue to move at a steady speed in a straight line unless a resultant force is acting.

Common misconception

Pupils believe driving forces are needed to keep objects moving at constant speed.

Demonstrate that friction (and drag) bring objects to a stop, showing that different surfaces produce the forces that slow objects.

Keywords

  • Stationary - A stationary object is not moving.

  • Resultant force - A resultant forces the sum of all forces acting on an object.

  • Frictional force - Frictional forces act between surfaces, to oppose the movement of an object.

  • Gravitational force - The gravitational force on an object pulls it downwards, towards Earth.

A linear air track is an excellent way to show motion with very low friction. Use one here to show the trolley and string experiment, demonstrating the examples provided instead of saving the apparatus for key stage four.
Teacher tip

Equipment

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision 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).

Video

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Starter quiz

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6 Questions

Q1.
What can make an object speed up, slow down, change direction or change shape?
Correct Answer: force, a force, forces, the force, resultant force
Q2.
What is the name of the force which is produced when two solid surfaces rub against each other?
upthrust
drag
Correct answer: friction
thrust
tension
Q3.
What is the name of the force that opposes movement when a solid object passes through a liquid or gas?
upthrust
Correct answer: drag
friction
thrust
tension
Q4.
A firework has a weight of 0.2 N and it produces an upwards thrust of 1.0 N when launched. What it the resultant force on the firework?
0.2 N upwards
1.0 N downwards
1.2 N upwards
0.8 N downwards
Correct answer: 0.8 N upwards
Q5.
Someone pushes a trolley along a flat road until it is moving quickly. They then jump on for a ride, putting both their feet up. Which of these statements is correct after they are on the trolley?
An image in a quiz
The force of friction will push the trolley forwards.
A push force is still driving the trolley forwards.
Correct answer: There is no force pushing the trolley forwards.
Fiction and drag will cause the trolley to immediately stop.
Correct answer: Friction and drag will cause the trolley to gradually slow down.
Q6.
A child lets go of a bundle of ten large helium balloons, each has a weight of 0.5 N. Each balloon produces an upthrust of 1 N. What is resultant force on the bundle of balloons?
An image in a quiz
0.5 N upwards
1.5 N upwards
5.0 N downwards
Correct answer: 5.0 N upwards
0 N
Q5 UYSEG

Exit quiz

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6 Questions

Q1.
Match the key word to the definition.
Correct Answer:stationary,not moving

not moving

Correct Answer:friction,force between two surfaces in contact when one tries to move

force between two surfaces in contact when one tries to move

Correct Answer:resultant force,the sum of the forces on an object accounting for direction

the sum of the forces on an object accounting for direction

Correct Answer:gravitational,a force that pulls objects towards Earth

a force that pulls objects towards Earth

Correct Answer:acceleration,a change in speed or direction of movement

a change in speed or direction of movement

Q2.
Which of these is an example of an object that has no propelling (forwards acting) force?
A car speeding up as it travels along a road.
A rocket taking off from a launchpad.
A shopping trolley being pushed by a customer.
Correct answer: A marble rolling along a flat desk.
A sled being dragged by some dogs.
Q3.
Which of these are true when there is no resultant force acting on an object?
It cannot be moving.
It must be moving.
Correct answer: If it is stationary it will remain stationary.
Correct answer: If it is moving it will stay moving at the same speed in the same direction.
If it is moving it must change speed or direction.
Q4.
The figure shows two forces acting on a lorry. What is the resultant force on the lorry?
An image in a quiz
0 N
400 N backwards
Correct answer: 400 N forwards
1600 N backwards
1600 N forwards
Q5.
The figure shows two forces acting on a moving lorry. What will happen to the lorry?
An image in a quiz
It will stop moving immediately.
It will speed up.
Correct answer: It will slow down.
It will start moving backwards.
It will stay at the same speed.
Q6.
A bowling ball is launched from a ramp along a bowling alley as shown in the figure. Which of the following statements are true?
An image in a quiz
Correct answer: The ball is at its highest speed at point B.
Correct answer: There is no force acting forwards between B and C
There is no resultant force on the ball between B and C.
The ball speeds up between points B and C.
Correct answer: A frictional force acts on the ball between points B and C.
Q4 UYSEG Q5 UYSEG Q6 UYSEG