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| We cannot see forces. | We can see and sometimes feel the effects they have on things. |
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The balloon in the picture is affected by forces. |
| Forces can make things speed up. | When you hit a tennis ball it speeds up. |
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| Forces can make things slow down or stop. | A parachute can make an object slow down because of air resistance. |
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| Forces can make things change direction. | You can make a cricket ball change direction by hitting it with a bat. |
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| Forces can make things change shape. | If you squeeze or kick a football, it will be compressed. |
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| Forces can make things turn. | You can use a spanner to slacken or tighten a nut. |
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| We measure force in newtons. | We use an instrument called a spring balance known as a force meter or a newton meter. |
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| Forces usually act in pairs. | ||||
| Forces act in a particular direction. |
