heat system efficiency??

[jin]

So lost..so what am i suppose to do??

'An engine absorbs 400J of heat and does 120J of work in each cycle'

a)what is its efficiency?
b)how much heat is rejected in each cycle?

[spacetime]

For a cycle, that is, when after a process, a system comes back to its original state, the difference of the net energy taken and work done by it is zero - first law of thermodynamics.

Efficiency = \frac{work done}{energy taken}


spacetime
www.geocities.com/physics_all/index.html

[jin]

so...i just go 120/400 x 100?

how do i calculate th heat rejected in the cycle?? the left over? 400-120??

[spacetime]

correct!

spacetime

[jin]

thanks! can u help me with the others on another post?? please ><