Question

A glass ball hanging from the hook of a sensitive spring balance is completely submerged in highly salty water and tap water, one by one. If the readings of spring balance when the ball is in highly salty water and tap water are x and y respectively, then :
(1) x < y
(2) x > y
(3) x = y
(4) x = 2y

Answer 1

When a body is immersed in a liquid it feels an upward force, which is known as buoyant force. The buoyant force depends upon the weight of the liquid displaced by the body.

In the given case, the same glass ball is being submerged in both the liquids, so the volume of water displaced will be the same in both cases. But the density of the highly salty water is more than the normal tap water, so the weight of the liquid displaced in case of highly salty water will be more. As a result, the glass ball will feel a more upward force when immersed in salt water. So the spring balance reading will be less for salty water and more for tap water. i.e. x < y.

Hence, the correct answer is option 1.