Question

C part of the last question

An object weighs 80 g in air and 70g in water . Calculate the buoyant force exerted by water and volume of object

Answer 1

weight of object in air = 80 * 10

                                    =  800 N (neglecting the air resistance)

weight of object in water = 70 * 10

                                         = 700 N

Buoyant force = Actual weight - Apparent weight

                       =   800 - 700

                          = 100 N

10 is gravitational acceleration

Answer 2

Given:

Mass of body in air =  M = 80/1000 grams

Mass of body in water = m = 70/1000 grams

To Find:

Buoyant Force by water = ?

Solution:

First of all,

the 'Weight of the body in air = Mg = 80 grams/1000 * 10 m/s

then,

The weight of the body in water = Mg - Buoyant Force

hence,

mg = Mg - Buoyant Force

As the buoyant force applied a force opposite to that of the force exerted by the weight.

Hence,

Buoyant Force = Mg -mg

Buoyant Force =  80/1000 *10 - 70/1000 * 10

Buoyant Force =  0.8N - 0.7N

Buoyant Force =  0.1N