Websink Prep UKKS2 ScienceYear 3 chaptersScience textbooksYear 1Year 2Year 3Year 4Year 5Year 6Year 7Year 8Year 9Browse allPast papersFind a tutorBecome a tutor
Primary Science · Year 3Chapter 9 · Forces
Year 3 Science · Forces · Lesson 9.2

Year 3 Science: Forces change how things move

Part of the Year 3 Science forces chapter. Chapter overview · whole chapter on one page

9.2

Forces change how things move

Year 3
F: forces act on objects and can make them start, stop, speed up, slow down or change direction
Story. Mo kicks a football that is lying still on the grass, and it starts to roll. Priya stops it with her foot. Mr Patel says, “The kick and the stop were both forces. Each one changed how the ball moved.”

A force acts on an object. When a force acts on an object, it can change the way the object moves. A force can make an object:

The picture shows each of these, with the force in orange and the motion in blue.

Starta push starts it movingStopa hand stops itSpeed upa push makes it fasterSlow downa force slows it downChange directiona kick sends it a new wayforcemotion
A force can start, stop, speed up, slow down or change the direction of a ball.

The table shows what a force can do, with an example for each.

What the force doesExample
starts an object movingA kick starts a football moving
stops a moving objectA hand stops a rolling ball
makes an object go fasterA push makes a trolley speed up
makes an object go more slowlyFriction slows a sliding box
changes the direction of an objectA kick from the side sends a ball off in a new direction

Key ideas

  • A force acts on an object.
  • A force can start an object moving, or stop a moving object.
  • A force can make an object speed up, slow down or change direction.
  • A force that pushes against the direction of motion slows the object down, or stops it.
Worked example 9.2.1
Look at the table in section 9.2. Which effect is shown by a hand that stops a rolling ball? Write the words.

Method. Find the row about the hand.

  1. Find the row. The row says a hand stops a rolling ball.
    A hand stops a rolling ball
  2. Read the effect. The effect in that row is stops a moving object.
    stops a moving object
  3. Write the answer.
    stops a moving object

Check. The hand pushes against the ball, so the ball stops. ✓

Watch out. The first column gives the effect. The second column gives an example.

Worked example 9.2.2
A still trolley is pushed, and it starts to roll. Which effect does the push have? Write the words.

Method. Think about the trolley before and after the push.

  1. Before the push. The trolley was still.
    still
  2. After the push. The push made the still trolley start moving.
    starts moving
  3. Write the answer.
    starts an object moving

Check. A force can start a still object moving. ✓

Worked example 9.2.3
A ball rolls on grass. The grass pushes against it, and the ball slows down. Does this force make the ball go faster or more slowly? Write the words.

Method. Think about the direction of the force.

  1. Find the direction of the force. The grass pushes against the ball, which is the opposite way to its motion.
    against the motion
  2. Decide the effect. A force that acts against the motion makes the ball go more slowly.
    more slowly
  3. Write the answer.
    more slowly

Check. Friction from the grass slows the ball. ✓

Watch out

Watch out: a force does not have to make an object go faster. A force that pushes against the direction of motion slows the object down, or stops it.

Try it at home or school (with a grown-up). Roll a small ball gently along a clear floor indoors, with a grown-up watching. Give it one gentle push to start it. Then stop it with your foot or a hand. Say which force started the ball and which force stopped it. Keep well away from stairs, doors and the edge of a table.

Exam tip

Grown-up tip. Ask: “What made the ball start moving? What made it stop? Did it speed up, slow down or change direction?” Let your child use the words force, start and stop.

Exercise 9B  Forces change how things move

1
FCan a force start a still ball moving? Write yes or no.
2
FLook at the table in section 9.2. Which effect is shown by a kick that starts a football moving? Write the words.
3
FIs a hand that stops a rolling ball applying a force to the ball? Write yes or no.
4
FFill in the gap: a force can make a moving object go more ___. Write the word.
5
FFill in the gap: a force can make an object change ___. Write one word about the way it moves.
6
FLook at the table in section 9.2. Which effect does a push on a trolley have when it speeds up? Write the words.
7
FA ball is rolling. Mei kicks it sideways, and it moves off in a new direction. Write the effect of the kick, in two words.
8
PSPriya says a force can only make things move faster. Is Priya right? Write no or yes.
9
PSAli pushes a still box, and it starts to move. Write the word for the effect: start, stop, speed up, slow down or change direction.
10
PSWorking scientifically. Predict what will happen to a rolling ball if a hand is held in its path. Write one prediction.
11
RWrite one sentence that explains how a force can change the motion of a ball.

Websink Prep UK is an independent site. It is not affiliated with, endorsed by or sponsored by AQA, Pearson Edexcel, OCR, WJEC, Eduqas, CCEA, SQA, GL Assessment, CEM or the Department for Education. All exam board names and trademarks belong to their owners. Past papers are linked from the exam boards' own websites and are not hosted here.

About Websink Prep UK · Find a tutor · Privacy · Terms · Cookie settings