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An electric heater supplies heat to a...

An electric heater supplies heat to a system at a rate or 100 W. If the system performs work at a rate of 75 joules per second at what rate is the internal energy increasing ?

Text Solution

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Heat supplied per second dQ = 100 J
work done by system per second dW = 75 J
Increases in internal energy `//` second `(alpha U ) = ?`
From first law of thermodynamic
`rArr dQ = dU + dW , dU = dQ - dW`
`dU = 100 J - 75 J`
`dU = 25 J s^(-1)`
`:. dU = 25 W`
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