Acar is designed to get its energy from a rotating
flywheelwith a radius of 1.50 m and a mass of475 kg. before a trip,
the flywheel isattached to an electric motor, which brings the
flywheel'srotational speed up to 4000 rev/min.
(a) find the kinetic energy stored in
theflywheel.
b) if the flywheel is to supply energy to the car as would a15.0-hp
motor, find the length of timethe car could run before the flywheel
would have to be brought backup to speed.

(a). The kinetic energy stored in  the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

Explanation:

Given that,

Radius = 1.50 m

Mass = 475 kg

Power

Rotational speed = 4000 rev/min

We need to calculate the moment of inertia

Using formula of moment of inertia

Put the value into the formula

(a). We need to calculate the kinetic energy stored in  the fly wheel

Using formula of K.E

Put the value into the formula

(b). We need to calculate the length of time the car could run before the flywheel  would have to be brought backup to speed

Using formula of time

Hence, (a). The kinetic energy stored in  the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

the answer would be a