27. each piston of an engine makes a sharp sound every other revolution of the engine. (a) how fast is a race car going if its eight-cylinder engine emits a sound of frequency 750 hz, given that the engine makes 2000 revolutions per kilometer? (b) at how many revolutions per minute is the engine rotating?

a)V= 93.75 m/s

b)The number of revolution per minute = 11,250 rev/min

Explanation:

Given that

Number piston , n =8

 Frequency ,f= 750 Hz

Revolution(R) = 2000 revolutions per kilometer

frequency of each piston

f'=f/n

f'=750/8

f'=93.75 Hz

So the number of revolution made by piston(r) = 2 x 93.75 rev/s

number of revolution made by piston(r) = 187.5 rev/s

The number of revolution per minute = 187.5 x 60 rev/min

The number of revolution per minute = 11,250 rev/min

So the speed of car V given as

r =number of revolution per second

R = revolutions per kilometer

V= 93.75 m/s

object 2 because all the other ones are wrong

i think the answer would be reserve.