An automobile engine has an efficiency of 19.0%. if it produces 23.0 kj of mechanical work per second, the heat rejected per second from the engine is closest to: (a) 77.0 kj (b) 81.5 kj (c)86.5 kj (d) 92.0 kj (e) 98.1 kj

(e) 98,1 KJ

Explanation:

The engine produces 19%; it means, it rejects 81% of energy. ⇒ 81/19=4.26 times.

The engine produces 23 kJ; it means it rejects 23 * 4.26 = 98.05263 kJ

see earlier

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.