A strong man stands with a heavy log on his shoulders. The log presses down on him with a force of 300 newtons. He stands like this for 10 minutes. How much work has he done? Explain your answer.
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Question No. 3
A man pushes against a truck. He uses a force of 60 newtons and he pushes the truck a total of five metres. How much work has he done? Show your working neatly and clearly.
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Question No. 4
A mass of 100 kg is dropped from an aircraft flying 500 metres above the sea. How much work has gravity done on the body when it hits the water? Ignore friction.
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Question No. 5
‘Mechanical energy’ can be divided into two types. What are they?
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Question No. 6
A ‘grandfather clock’ uses a pendulum to regulate its mechanism. Would a grandfather clock work in deep space – millions of kilometres from the nearest body? Explain your answer.
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Question No. 7
Explain why the water in a dam may be said to have potential energy.
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Question No. 8
A child pushes her toy box one metre along the floor of her room. Even though she is moving the box horizontally, and therefore not working against the force of gravity, she does perform work in this activity. Briefly explain why work is performed.
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Question No. 9
A man uses a total force of 900 N to carry his suitcase up some stairs. The vertical height of the stairs is three metres. He takes 10 seconds to do this. Calculate the amount of work he has performed and the power he has used. Show your working neatly and clearly.
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