Question

If the indicated power of an IC engine at NO-LOAD condition is 0.5 kW, then the friction power is ______ kW.

• A. 1
• B. 2
• C. 0.5
• D. 0

Hint:

At no load the brake power is zero, so think about where the indicated power goes.

Answer 1

The Correct Option is C

This question tests the basic power balance of an IC engine and what no load means for that balance.

1. 1 kW: This would need the friction power to be double the indicated power, which cannot happen because friction power can never exceed the indicated power that produces it.
2. 2 kW: This is four times too large, and there is no physical reason for friction power to exceed indicated power at no load.
3. 0.5 kW: At no load the engine delivers no useful output, so brake power BP is zero. Since indicated power equals BP plus friction power, all 0.5 kW of indicated power is spent overcoming friction, giving FP = 0.5 kW. This matches the given data exactly.
4. 0 kW: This would mean the engine has no internal friction at all, which is not realistic since fuel still burns to keep the engine running with no external load.

The correct choice is (C): the friction power is 0.5 kW, equal to the indicated power measured at no load.