Question

An electric heater supplies heat to a system at a rate of 200 watts. If the
system performs work at a rate of 150 joules/sec. at what rate is the
internal energy increasing?
​

Answer 1

$\red{\textbf{Answer}}$

$\blue{\texttt{the electric heater supplied ,}}$
$\blue{\texttt{heat to the system at a rate of,}}$

$\textbf{200W}$

∴$\blue{\textbf{Heat supplied, }}$

$\textbf{Q=200}$ J/s

$\blue{\texttt{The system performs at a rate of}}$ $\textbf{150}$J/s.

∴$\blue{\textbf{Work done,}}$

$\textbf{W = 150}$ J/s

$\blue{\texttt{according to the ,}}$

$\blue{\texttt{first law of thermodynamics, }}$

$\blue{\textbf{we have,}}$

$\textbf{Q= U+ W}$

$\blue{\texttt{(Where,U = Internal energy) }}$

∴$\textbf{U=Q-W}$

= 200 – 150

= 50 J/s

=50 W

$\red{\textbf{Therefore, the internal energy }}$
$\red{\textbf{of the given electric heater increases at a rate of ,}}$

$\textbf{50W}$.

Answer 2

$\bold{Hii\: dear}$

_________

∆U = 200W = 200J/s

∆W = 150J/s

increase in internal energy, ∆U = ?

∆Q = ∆U + ∆W

•°• ∆U = ∆Q - ∆W = 200 - 150

= $\bold{50}$J/s

rate is the $\bold{internal}$energy increasing is 50 j/s