Question

PLEASE HELP!!!!!!!!!!!

in a heat engine if 1000 j of heat enters the system and the piston does 500j of work, what is the final internal energy of the system if the inital energy was 2000 j

1.write the equation
2.list out your known variables
3. plug the numbers into the equations
4.solve
5.write your solution statement that includes initial energy and final energy added.

Answer 1

As we know that from first law of thermodynamics we have

$Q = \Delta U + W$

here we know that

Q = heat given to the system

W = work done by the system

$\Delta U$ = change in internal energy of the system

now we will have

Q = 1000 J

$U_i = 2000 J$

Work done by the piston = 500 J

so work done by system of gas = -(work done by piston)

$W_g = -500 J$

now from above equation we have

$1000 J = - 500 + \Delta U$

$\Delta U = 1500 J$

now we know that

$\Delta U = U_f - U_i$

$U_f - 2000 = 1500 J$

$U_f = 3500 J$

So final internal energy of the gas is 3500 J while initial internal energy is given as 2000 J