Question

A stone weight is 10N in air and 7N in the water

A. Calculate the buoyancy exerted by water on stone?

B. What is the weight of stone, when it is dipped in the saline water

C. Compare the density of saline water and water?​

Answer 1

Answer:

Let's say weight of body in vac=W ( on earth )

Buoyancy force in Air = Ba

Buoyancy force in water = Bw

Buoyancy in a fluid = weight of fluid displaced

Let's say volume of body = V

Therefore, Ba = V x air density

And Bw = V x density of water

Now, W - Ba = 10………. (1)

And W - Bw = 7…………(2)

(1)-(2) =>

Bw - Ba = 3

V(997–1.225) kg/m3 = 3 N

V = .00030710792 m3

Therefore buoyancy force by water

Bw = V x 997 x 9.81 N

Bw = 3.0036905 N

Bonus

By (1), W - Ba = 10

W = V m3 x (1.225 x 9.81) N/m3 + 10 N

W = 10.0036905 N