If the thermal energy of a system increases by 400 j, and 1100 j of heat was added to the system how much work did the system do?

The equation used here is ΔU=Q-W,

where, ΔU is the change in the system's internal energy, Q is the energy transferred to or from the system by heat, and W is the energy transferred to or from the system by work.

Known:

ΔU=400J

Q=1100 J

W=?

Plug into the equation:

400=1100-W

Therefore W=700 J.

So the system did 700 J of work.