Question

A rubber ball filled with air has a diameter of 25.0 cm and a mass of 0.540 kg. What force is requiered to hold the ball in equilibrium immediately below the surface of water in a swimming pool?

Start equation out by using sumF = ma
Answer is 74.9 N
I just need to know how to work it and start it out.
Thx

Answer 1

force bouyance= weight+ forceholdingit down.

bouyancy is the weight of the water it displaces, or densitywater*g*volume or
= 4/3 PI r^2 * density water*g

where density water is in kg/m^3, r is in meters, SI throughout.

Answer 2

Ok cool thanks! Is there anyway to start the equation out with sumF = ma though? That is what my teacher stated to do on the paper.

Answer 3

Since the ball is being held, it is not accelerating. Therefore a = 0

That leads to
sumF = 0

Then follow BobPursley's advice

Answer 4

Alrighty sounds good. Got it. THx