Answer: Option 1
When indicated power (I.P.) and frictional power (F.P.) are known, we can calculate Brake power
Friction Power = Indicated power - Brake Power
Answer: Option 2
The mechanical efficiency (ηm) of an I.C. engine is equal to B.P/I.P.
where
I.P. = Indicated power,
B.P. = Brake power
F.P. = Frictional power