Question

Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel. During the process, 30 kJ of heat is transferred to the water, and 5 kJ of heat is lost to the surrounding air. The paddle-wheel work amounts to 5000 N m. Determine the final energy of the system if its initial energy is 10 kJ.

Answer 1

Final energy will be 40 KJ

Step-by-step explanation:

We have given that 30 KJ of the heat is transferred to the water

So
`Q_1=30kj`

And 5 KJ of heat is lost to the surrounding air

So
`Q_2=-5kj`

So total heat
`Q=Q_1+Q_2=30+(-5)=25KJ`

The paddle-wheel work amounts to 5000 N -m

So work done W = -5 KJ ( as work is done by the paddle wheel )

We know that
`Q=W+\Delta U`

`25=-5+\Delta U`

`\Delta U=30KJ`

We have given initial kinetic energy = 10 KJ

So
`final -initia=30`

`final-10=30`

So final energy = 30+10 =40 KJ