# A block of mass 7 kg and volume 0.07 m3 floats in a liquid of density 140 kg/m3. Calculate: Volume of block above the surface of liquid. Density of block. - Physics

Sum

A block of mass 7 kg and volume 0.07 m3 floats in a liquid of density 140 kg/m3. Calculate:

1. Volume of block above the surface of liquid.
2. Density of block.

#### Solution

Mass of block = m = 7 kg

Volume of block = V = 0.07 m3

Density of liquid =ρl = 140 kgm-3

Let V’ = Volume of block immersed in the liquid

By law of floatation:

Weight of block = Weight of liquid displaced by the immersed pa

"V"'rho"g" = "V"'rho_l "g"

"V"' = rho/rho_l V

Density of block = rho = "m"/"V" = 7/0.07 = 100 kg m-3

From (1)

"V"' = (100 "V")/140 = 5/7 "V" = 5/7 xx 0.7

"V"' = 1/20 = 0.05 m3

Volume of block above the surface of liquid = V = V1

= 0.07 - 0.05 = 0.02 m3

Concept: Archimedes' Principle
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#### APPEARS IN

Goyal Brothers Prakashan Class 9 A New Approach to ICSE Physics Part 1
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