Question

A body of brass has a mass of 750 g and a density of 8 x 103 kg m-3. It is suspended from a
string. Calculate its weight in the water.​

Answer 1

Given :-

Mass of brass in air (m) = 750g = 0.75kg

Density of brass (d) = 8 × 10³ kgm^{-3}

To find :-

Weight of brass in water.

Point to remember :-

Upthrust = Weight of water displaced

Weight of brass in water = weight in air - upthrust

Solution :-

Weight of brass in air = 0.75 × 10 = 7.5N

Vol. of water displaced = Vol. of brass

= m/d = 0.75/8000 = 9.375 × 10^{-5} m³

Upthrust = Weight of water displaced

= Mass of water displaced × 10

= Vol. of water displaced × Density of water × 10

= 9.375 × 10^{-5} × 10³ × 10

= 0.9375N

Weight of brass = weight in air - upthrust

= 0.75 × 10 - 0.9375

= 7.5 - 0.9375

= 6.5625 N

Answer :-

Weight of the body of brass in water = 6.5625 N.

Answer 2

Answer:

Explanation:

Given :-

Mass of brass in air (m) = 750g = 0.75kg

Density of brass (d) = 8 × 10³ kgm^{-3}

To find :-

Weight of brass in water.

Point to remember :-

Upthrust = Weight of water displaced

Weight of brass in water = weight in air - upthrust

Solution :-

Weight of brass in air = 0.75 × 10 = 7.5N

Vol. of water displaced = Vol. of brass

= m/d = 0.75/8000 = 9.375 × 10^{-5} m³

Upthrust = Weight of water displaced

= Mass of water displaced × 10

= Vol. of water displaced × Density of water × 10

= 9.375 × 10^{-5} × 10³ × 10

= 0.9375N

Weight of brass = weight in air - upthrust

= 0.75 × 10 - 0.9375

= 7.5 - 0.9375

= 6.5625 N

Answer :-

Weight of the body of brass in water = 6.5625 N.