Find the time required to complete each cycle

[sun]

Homework Statement

A particular engine has a power output of 6.00 kW and an efficiency of 26.0%. Assume the engine expels 6000 J of energy in each cycle.

(a) Find the energy absorbed in each cycle.
(b) Find the time required to complete each cycle.

P=W/delta t
e=W/Q

1kW=3.6x10^6J

Because the engine is expelling 6000J, does this mean it is negative? I'm not quite sure how to approach this problem.

 

[gtn]

I suspect that if you start with a unit analysis the solution will jump out.

Gary

 

[sun]

Things aren't that obvious to me :(.

I came to the realization that 1kW=3.6x10^6J, so 6kW=2.16x10^7J.

 

[gtn]

Things aren't that obvious to me :(.

I came to the realization that 1kW=3.6x10^6J, so 6kW=2.16x10^7J.

kW aren't directly convertable to J. 1J = 1W x 1s or one Joule equals one Watt-Second. What you have is the conversion of a kW-hr (kilowatt-hour) to a Joule.

The Watt is a measure of power. The Joule a measure of energy. To move between power and energy time must be considered.

Gary