A boy is sitting on a rotating chair with his arms folded. If he suddenly extends his arms, what will happen to his angular velocity? MCQ with Answer and Explanation
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Question #1
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The work done by a conservative force acting on a particle moving around any closed path is:
Correct Answer: Option B
Explanation:
By definition, a force is conservative if the work done by it on an object moving between two points is completely independent of the path taken. A direct consequence of this is that the total work done by a conservative force (like gravity or electrostatic force) in moving an object around a closed loop (returning to the starting point) is exactly zero.
By definition, a force is conservative if the work done by it on an object moving between two points is completely independent of the path taken. A direct consequence of this is that the total work done by a conservative force (like gravity or electrostatic force) in moving an object around a closed loop (returning to the starting point) is exactly zero.
Question #2
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A capillary tube is dipped in water and the water rises to a height 'h'. If the experiment is performed in a freely falling elevator, the water column in the tube will:
Correct Answer: Option A
Explanation:
The height of capillary rise is given by Jurin's law: h = 2Tcos(theta) / (rrhog). In a freely falling elevator, the effective acceleration due to gravity (g') is zero (weightlessness). As effective g approaches zero, the theoretical height h approaches infinity. In reality, the water will rise to the very top of the tube, regardless of its length, but will not overflow.
The height of capillary rise is given by Jurin's law: h = 2Tcos(theta) / (rrhog). In a freely falling elevator, the effective acceleration due to gravity (g') is zero (weightlessness). As effective g approaches zero, the theoretical height h approaches infinity. In reality, the water will rise to the very top of the tube, regardless of its length, but will not overflow.
Question #3
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Why does a metal spoon feel colder than a wooden spoon when left in a cold room, despite both being at the same room temperature?
Correct Answer: Option B
Explanation:
Both spoons are at the same temperature. However, metal is a good conductor of heat. When you touch it, it rapidly conducts heat away from your hand, making your skin feel a sudden drop in temperature (which you perceive as 'cold'). Wood is a poor conductor, so it draws heat from your hand very slowly.
Both spoons are at the same temperature. However, metal is a good conductor of heat. When you touch it, it rapidly conducts heat away from your hand, making your skin feel a sudden drop in temperature (which you perceive as 'cold'). Wood is a poor conductor, so it draws heat from your hand very slowly.
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