Question

A large container of water is sitting on a balance. The weight of the container plus the water is 10 newtons. An object the weight of 7 newtons hanging from a forcemeter is lowered towards the surface of the water . what reading on the force meter would you expect?

Answer 1

3N

Step-by-step explanation:

Note that when an object is immersed in water it weighs less.

This means the weight seen is the apparent weight.

Now in water there is upthrust and is a counter force acting on the object and this force is opposite to the weight of the fluid alongside the container 10N

The apparent weight is the real weight - the upthrust

7N-10 = -3N

The essence of the negative sign is to show that this force is acting in opposite direction to the weight.

Note: the upthrust is 10N and it's opposite to the weight of the fluid and the tube on which the object on the force meter is subjected to.