Q88 / 90 · JEE Main 2021 (26 Aug Shift 2) · Physics

The acceleration due to gravity is found up to an accuracy of 4% on a planet. The energy supplied to a simple pendulum of known mass m to undertake oscillations of time period T is being estimated. If time period is measured to an accuracy of 3%, the accuracy to which E is known as ________%

Correct answer: 14

Solution

T=2πlg

Δll×100=Δgg×100+2ΔTT×100

⇒Δll×100=4+2×3=10%

E=12mω2A2=12mglA2Therefore, ΔEE×100=Δgg×100+Δll×100=4+10=14%

Hence, the correct answer is 14.

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