Complete the following tables: Mass ( kg ) Volume ( m 3 ) Density ( kg m 3 ) 350 175 - - 190 4 Density of metal( kg m 3 ) Density of water ( kg m 3 ) Relative density - 10 3 5 8 . 5 × 10 3 10 3 - Weight ( N ) Area ( m 2 ) Pressure ( N m - 2 ) - 0 . 04 20000 1500 500 -

We know that, Density = Mass Volume = 350 175 = 2 kg / m 3 Mass = density × volume = 4 × 190 = 760 kg Mass ( kg ) Volume ( m 3 ) Density ( kg m 3 ) 350 175 2 760 190 4 Relative density = Density of metal Density of water Density of metal = Density of water × relative density = 10 3 × 5 kg / m 3 Relative density = Density of metal Density of water = 8 . 5 × 10 3 10 3 = 8 . 5 Density of metal ( kg / m 3 ) Density of water ( kg / m 3 ) Relative Density 5 × 10 3 10 3 5 8 . 5 × 10 3 10 3 8 . 5 Force = pressure × area = 20000 × 0 . 04 = 800 N Pressure = Force Area = 1500 500 = 3 N m - 2 Weight ( N ) A r e a ( m 2 ) Pressure ( N m 2 ) 800 0 . 04 20000 1500 500 3

The density of a metal is 10 . 8 × 10 3 kg / m 3 . Find the relative density of the metal.

Relative density of a substance is called its ‘specific gravity.’ R e l a t i v e d e n s i t y = D e n s i t y o f s u b s tan c e D e n s i t y o f w a t e r Data Given: Density of metal = 10 . 8 × 10 3 kg / m 3 We know that Density of water = 10 3 kg / m 3 So, The relative density = 10 . 8 × 10 3 10 3 = 10 . 8

E M B I B E

General Science>Chapter 3 - Force and Pressure>Exercises>Q 3

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8th Maharashtra Board

IMPORTANT

Earn 100

How much pressure do we carry on our heads? Why don’t we feel it?

Important Questions on Force and Pressure

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 4

Why does it happen?

A ship dips to a larger depth in freshwater as compared to marine water.

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 4

Fruits can easily be cut with a sharp knife. Why does it happen?

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 4

The wall of a dam is broad at its base. Why does it happen?

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 4

If a stationary bus suddenly speeds up, passengers are thrown in the backward direction. Why does it happen?

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 5

Complete the following tables:

Mass ( $kg$ )	Volume ( $m^{3}$ )	Density ( $\frac{kg}{m^{3}}$ )
$350$	$175$	-
-	$190$	$4$

Density of metal( $\frac{kg}{m^{3}}$ )	Density of water ( $\frac{kg}{m^{3}}$ )	Relative density
-	$10^{3}$	$5$
$8.5 \times 10^{3}$	$10^{3}$	-

Weight ( $N$ )	Area ( $m^{2}$ )	Pressure ( $N m^{- 2}$ )
-	$0.04$	$20000$
$1500$	$500$	-

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 6

The density of a metal is

10.8 \times 10^{3} kg / m^{3}

. Find the relative density of the metal.

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 7

Volume of an object is

20 {cm}^{3}

and the mass in

50 g

. Density of water is

1 g / {cm}^{3}

. Will the object float on water or sink in water?

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8th Maharashtra Board

IMPORTANT

General Science>Chapter 3 - Force and Pressure>Exercises>Q 8

The volume of a plastic covered sealed box is $350 {cm}^{3}$ and the box has a mass $500 g$ . Will the box float on water or sink in water? What will be the mass of
water displaced by the box?

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