A metal ball of surface area 200 c m 2 and temperature 52 7 ∘ C is surrounded by a vessel at 2 7 ∘ C. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is nearly ( σ = 5.67 × 1 0 − 8 W m − 2 K − 4 ):

P = ε σ A ( T 4 − T 0 4 ) = 0.4 × 5.67 × 1 0 − 8 × 0.02 × ( 80 0 4 − 30 0 4 ) = 182 W. The nearest option is 186 J per second. C.

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Physics - Heat & Thermo Question with Solution | TestHub

PhysicsHeat & ThermoHeat TransferMedium2 min

PhysicsMediumsingle choice

A metal ball of surface area 200 $c m^{2}$ and temperature $52 7^{\circ}$ C is surrounded by a vessel at $2 7^{\circ}$ C. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is nearly ( $σ = 5.67 \times 1 0^{- 8}$ W $m^{- 2}$ $K^{- 4}$ ):

Options:

Answer:

Solution:

$P = ε σ A (T^{4} - T_{0}^{4}) = 0.4 \times 5.67 \times 1 0^{- 8} \times 0.02 \times (80 0^{4} - 30 0^{4}) = 182$ W. The nearest option is 186 J per second. C.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Heat Transfer

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