To determine which car has the greatest kinetic energy, we can calculate the kinetic energy for each scenario using the formula KE = (1/2)mv^2, where KE is the kinetic energy, m is the mass, and v is the velocity.
For scenario A:
KE = (1/2)(500 kg)(30 m/s)^2 = 225,000 J
For scenario B:
KE = (1/2)(500 kg)(3 m/s)^2 = 2,250 J
For scenario C:
KE = (1/2)(500 kg)(21 m/s)^2 = 110,250 J
For scenario D:
KE = (1/2)(500 kg)(12 m/s)^2 = 36,000 J
Based on these calculations, we can conclude that scenario A - a car with a mass of 500 kg moving at 30 m/s - has the greatest kinetic energy of 225,000 J.