A metal of mass 1 kg at constant atmospheric pressure and at initial temperature `20^@C` is given a heat of 20000J. Find the following (a) change in temperature, (b) work done and (c) change in internal energy. (Given, specific heat `=400J//kg-^@C`, cofficient of cubical expansion, `gamma=9xx10^-5//^@C`, density `rho=9000kg//m^3`, atmospheric pressure `=10^5N//m^2`)

A metal of mass 1 kg at constant atmospheric pressure and at initial t

1.	A metal of mass 1 kg at constant atmospheric pressure and at initial temperature `20^@C` is given a heat of 20000J. Find the following (a) change in temperature, (b) work done and (c) change in internal energy. (Given, specific heat `=400J//kg-^@C`, cofficient of cubical expansion, `gamma=9xx10^-5//^@C`, density `rho=9000kg//m^3`, atmospheric pressure `=10^5N//m^2`)
Answer» Correct Answer - A (a) From `DeltaQ=msDeltaT` `Delta=(DeltaQ)/(ms)=(20000)/(1xx400)=50^@C` (b) `DeltaV=V_gammaDeltaT=(1/9000)(9xx10^-5)(50)` `=5xx10^-7m^3` `:.` `W=p_0*DeltaV=(10^5)(5xx10^-7)=0.05J` (c) `DeltaU=DeltaQ-W=(20000-0.05)J` `=19999.95J`

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