Chapter 8, Problem 18RQ

A balloon that weighs $1\text{N}$ is suspended in the air, drifting neither up nor down. How does the buoyant force acting on it compare with its weight? What happens if the buoyant force decreases? Increases?

To determine

The buoyant force acting on the balloon as compared to its weight and the effect of buoyant force on the balloon, when it is decreases and increases

Answer to Problem 18RQ

$1\text{N}$ of buoyant force will act on the balloon. The balloon will sink if the buoyant force decreases and it will float if buoyant force increases.

Explanation of Solution

According to Archimedes principle, the buoyant force acting on an object is equal to the amount of fluid displaced by the object. In this case, the balloon is fully immersed in the air, then the amount of fluid displaced by the balloon is equal to the weight of the balloon that is 1 Newton of buoyant force will act on the balloon.

The Archimedes principle also states that if the value of buoyant force is more than the weight of the balloon, then the balloon will float and if the buoyant force is less than the weight of the balloon, then it will sink in the downward direction.

Conclusion:

Therefore, the balloon will sink if the buoyant force decreases and it will float if buoyant force increases.