A hollow plastic ball is taken to the bottom of a trough of water and released there (see adjoining figure). (a) What happens to the ball? (b) Give reason for this phenomenon.

(a) The hollow plastic ball will come to the surface of the water and will float there. (b) The ball floats on water because the density of the ball is less than the density of water so the upthrust exerted by water on the ball overcomes its weight and thus makes it float on water.

E M B I B E

Together with Science Class 9>Chapter 10 - Gravitation>ASSESS YOURSELF>Q 13

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9th CBSE

IMPORTANT

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On what principle are submarines based?

Important Questions on Gravitation

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In which direction do fluids exert pressure?

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9th CBSE

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The head of a pin is flat and thick whereas its tip is fine and thin. Explain why? Write a formula that support your answer.

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When you press the head of a pin, it pierces into the board and not your thumb. Why?

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9th CBSE

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Why are railway tracks laid on large-sized concrete sleepers? Explain.

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Together with Science Class 9>Chapter 10 - Gravitation>ASSESS YOURSELF>Q 17

Explain why a truck or a motor bus has much wider tyres.

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9th CBSE

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Why do we feel lighter when we swim?

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9th CBSE

IMPORTANT

Together with Science Class 9>Chapter 10 - Gravitation>ASSESS YOURSELF>Q 19

A hollow plastic ball is taken to the bottom of a trough of water and released there (see adjoining figure).
Question Image
(a) What happens to the ball?
(b) Give reason for this phenomenon.