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.

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒