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
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?
A. It will decrease.
B. It will increase.
C. It will become zero.
D. It will remain the same.
Answer: Option A
Solution (By JKSSB Mock Tests)
This is based on the conservation of angular momentum (L = Iω), where 'I' is the moment of inertia and 'ω' is angular velocity. When the boy extends his arms, mass moves further from the axis of rotation, increasing his moment of inertia (I). Since 'L' is conserved, an increase in 'I' must result in a decrease in angular velocity (ω).
Explanation:
Potentiometer uses null method: at balance, no current flows through cell, so measured voltage equals true EMF (no internal resistance drop). Memory aid: 'Null method ⇒ zero current ⇒ accurate EMF measurement'. Experimental physics concept frequently tested in competitive exams to verify understanding of precision measurement techniques.
Explanation:
The Zeroth Law of Thermodynamics states that if body A is in thermal equilibrium with body B, and body B is in thermal equilibrium with body C, then A is also in thermal equilibrium with C. This transitive property implies a common physical property shared by them all, which we define as 'temperature'. A thermometer acts as body B.
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