Please i need help in this question thank you.A cube of cooper 2.00cm on a side is suspended by a string. The cube is heated with a burner from...

The volume of the cube is

`V
= d^3 =0.02^3 =8*10^-6 m^3`

The coefficient of volumetric
expansion for copper is `gamma=5.1*10^-6 K^-1`

The
increase in temperature is `Delta(T) =90-20 =70 K =70 @C`

The law of volume variation with temperature
is

`Delta(V) =gamma*V*Delta(T) =5.1*10^-6*8*10^-6*70
=2.856*10^-9 m^3`

`Delta(V) =2.856*10^-3 cm^3`

b)

The mechanical work done
by the cube to increase its volume against the  atmospheric pressure
is

`W =P*Delta(V) =1.01*10^5*2.856*10^-9 =2.885*10^-4 J`

c)

The mass of the cube
is

`m = rho*V = 8900*8*10^-6 =7.12*10^-2 kg =71.2 grams`

The heat necessary to increase the temperature of the cube
is

`Q =m*Cp*Delta(T) =7.12*10^-2*390*70=1943.76 J`

d) If `U` is the internal energy of the cube then the
first principle of thermodynamics says:

`Q =Delta(U) +W`

`Delta(U) =Q-W =1943.76-2.885*10^-4 =1943.7597 J`