Question

A piece of iron rests on top of a piece of wood floating in a bathtub. If the iron is removed from the wood, and kept out of the water, what happens to the water level in the tub?

a. It goes up.
b. It does not change.
c. It goes down.
d. It is impossible to determine from the information given.

Answer 1

It goes down.

The water level remain the same.

Step-by-step explanation:

This can be explained using Archimedes principle which states that a body fully or partially submerged in a fluid is acted by an upward bouyant force which is equal to the weight of the fluid the body displaced.

The wood will only sink if the weight of the wood is greater than the weight of the fluid the wood displaced, but the weight of the wood is equal to the weight of fluid displaced, therefore the wood will float.

Therefore, the weight of the wood is the same as the weight of the fluid displaced, so the wood will be at the same level as the water.

If the iron is removed, the level of the water goes down because iron weight is bigger than the water displaced and it tends to increase the water level but since it is removed, the water level will decrease.