compute the kinetic energy of an 1800 lb automobile traveling at 30 mi/hr. how many times as great is the kinetic energy if the velocity is doubled? compute the kinetic energy, in erg and in joules, of a 2 gram bullet travelling at 500 m/sec.

Answer 1

Mass = 1800Lb * 0.454kg/Lb = 817.2 kg

V=30mi/h * 1600m/mi * 1h/3600s=13.33 m/s

KE=0.5m*V^2 = 0.5*817.2*13.33^2 = 72,604 Joules.

KE = 0.5m*(2V^2) = .5m*4V^2 = 4 times
as great.

KE = 0.5*0.002*500^2 = 250 J.