Chapter 10, Problem 15Q

(a)

To determine

To Explain: Whether the level of water will rise, fall, or stay the same when the boat is removed from the water.

Explanation of Solution

Introduction:

Archimedes principle says that the buoyant force applied by liquid on the object is equal to the weight of the liquid displaced by the object.

When the boat is inside the water, it displaces water. So, the level of water rises since water is displaced. When the boat is removed from the water, no water is displaced in the swimming pool. Hence, the level of waterfalls in the swimming pool.

Conclusion:

On removing the boat from the water, the level of water in a pool falls.

(b)

To determine

To Explain:Whether the level of water will rise, fall, or stay the same when the iron anchor is removed from the boat and placed on the shore.

Explanation of Solution

Introduction:

As per the Archimedes principle, the buoyant force applied by liquid on the object is equal to the weight of the liquid displaced by the object.

Anchor when kept in boat displaces water as it has mass. Hence, the level of water is more when the anchor is inside the boat. When the anchor is removed and kept onshore, then the amount of water displaced reduces, and hence, its level falls.

Conclusion:

On removing anchor from the boat and keeping it onshore, the level of water in the swimming pool falls.

(c)

To determine

To Explain: Whether the level of water will rise, fall or stay the same is to be determined when the iron anchor is removed from the boat and dropped in the pool.

Explanation of Solution

Introduction:

Archimedes principle says that buoyant force exerted by the liquid on the object is equal to the weight of the liquid displaced by the object.

When the anchor is kept on the boat, it removes water equal to its weight and it is added mass to the boat. So, the volume of water displaced by it is more. In the pool, when the anchor is removed and dropped, it removes the volume of water equal to its volume. Since the density of iron is 7 times the density of water, it displaces lesser volume than it displaced when kept on a boat. Hence, there is a net decrease in the level of water.

Conclusion:

The level of water in a swimming pool falls when the anchor is removed from the boat and dropped in the pool.