Posted by Katie on .
The motion of a piston in an automobile engine is nearly simple harmonic. If the 1-kg piston travels back and forth over a total distance of 10.0 cm, what is its maximum speed when the engine is running at 3 000 rpm? The answer is 15.7 m/s but I don't understand how to get there.
displacement=Amax(SIN W T)
VELOCITY= aMAX*W*COS WT
Maximum speed is w A, where w is the angular velocity and A is the amplitude. The amplitude A is half the displacement of the engine, or 5.0 cm.
The angular velocity in your case is
w = (3000 rev/min)*(2 pi rad/rev)/(60 sec/min) = 314 rad/s
Vmax = 5.0*314 = 1570 cm/s = 15.7 m/s