Question Detail
Question
A flask of water rests on a scale. If you dip your finger into the water, without touching the flask, does the reading on the scale?
Correct Answer
Option A is the correct answer.
Detailed Explanation
When you dip your finger into the water, the water exerts an upward buoyant force on your finger. By Newton's third law, your finger exerts an equal and opposite downward force on the water. This additional downward force is transmitted through the water to the flask and then to the scale, causing the scale reading to increase by an amount equal to the buoyant force on your finger.
Hint
Consider Newton's third law: action-reaction pairs. The buoyant force on your finger has a reaction force on the water.