A solid disc spins in frictionless bearings. Its temperature is raised by 5 0 ∘ C ( α = 1.2 × 1 0 − 5 per °C). Choose all correct statements.

No external torque, so L is constant (A true). I grows as R 2 , so ω falls (B false) by 2 α Δ T = 2 ( 1.2 × 1 0 − 5 ) ( 50 ) = 1.2 × 1 0 − 3 (C true). KE = 2 I L 2 falls (D false). A, C.

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Physics - Heat & Thermo Question with Solution | TestHub

PhysicsHeat & ThermoThermal ExpansionMedium2 minQB

PhysicsMediummultiple choice

A solid disc spins in frictionless bearings. Its temperature is raised by $5 0^{\circ} C (α = 1.2 \times 1 0^{- 5}$ per °C). Choose all correct statements.

Options:(select one or more)

Answer:

A, C

Solution:

No external torque, so L is constant (A true). I grows as $R^{2}$ , so $ω$ falls (B false) by $2 α Δ T =$ $2 (1.2 \times 1 0^{- 5}) (50) = 1.2 \times 1 0^{- 3}$ (C true). $KE = \frac{L ^{2}}{2 I}$ falls (D false). A, C.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Thermal Expansion

⏱ 2mℹ️ Source: QB

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