2 L of water in a container is heated with a coil of 1 kW at 27 ℃ . The lid of the container is open and energy dissipates at rate of 160 J s - 1 . Find the time after which temperature will rise from 27 ℃ to 77 ℃ ? [Given specific heat of water is 4 . 2 kJ / Kg ]

Question

2 L of water in a container is heated with a coil of 1 kW at 27 ℃ . The lid of the container is open and energy dissipates at rate of 160 J s - 1 . Find the time after which temperature will rise from 27 ℃ to 77 ℃ ? [Given specific heat of water is 4 . 2 kJ / Kg ], 8 min 20 sec, 6 min 2 sec, 7 min, 14 min

MARKS App · Accepted Answer

Energy gained by water (in 1 s) = Energy supplied - energy lost = (1000 J-160 J)=840 J Total heat required to raise the temperature of water from 27 ℃ t o 77 ℃ i s m s ∆ θ . Hence, the required time, t = m s ∆ θ r a t e b y w h i c h e n e r g y i s g a i n e d b y w a t e r = 2 4.2 × 10 3 ( 50 ) 840 = 500 s = 8 min 20 s.

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