Question

A body of mass 100 N floats on water.
a. What is the weight of the body in water?
b. What is the force of buoyancy?
c. What is the weight of water displaced?​

Answer 1

Answer:

Given that,

Weight of body in air = 100 N

Buoyant force = Weight of liquid displaced

Volume of water displaced = 400 cc

2

Density of water = 1g/cm3

In this case,

ρ=

V

m

m=ρ×V

m=1×400

m=400g

We know that,

The weight of water displaced is

W=m×g

W=

5

2

×9.8

W=3.92N

Now, weight of the object in water

W=100−3.92

W=96.08

W=96N

Hence, the weight of object in water is 96 N

Answer 2

a) 0

b) 100N

c) 100N

Any object or mass will only float on a liquid or water if the buoyancy force acting on it by the liquid is equal to its weight. But according to Archimedes principle, we know that the buoyancy force by the liquid is equal to the weight of the liquid displaced.

So we can say that in the case of a floating body, the weight of the body = weight of water displaced

a) Since the buoyancy force and weight of the body is equal, therefore, it will cancel each other and the apparent weight of the body in water will be zero

b) Bf = weight of the body

here Bf is the buoyancy force

Therefore, Bf= 100N

c) weight of the body = weight of water displaced

So, the weight of water displaced = 100N.