Ice for Cooling Water – Rankers Physics

Heat Transfer - Conduction and Convection: Practice Problem & Solution

Assertion (A): Ice is placed at top of the bucket to cold the water. Reason (R): Heat transfer by convection takes place in upward direction.  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Heat Transfer - Conduction and Convection. Understanding the underlying formula is key to arriving at the correct answer below:

When ice is placed at the top, the water layer near the ice cools, becomes denser, and sinks. Warmer, less dense water from below rises to the top to be cooled by the ice. This sets up convection currents, efficiently cooling the entire volume. Thus, heat is transferred upwards to the ice by the rising warmer water. Both A and R are true, and R correctly explains A.

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