## Physics (10th Edition)

$$KE=\frac{1}{2}mv^2$$ $$\vec{p}=m\vec{v}$$ Kinetic energy is a scalar quantity, so it concerns only with the magnitude of velocity. Because 2 cars have the same mass and same velocity, they have the same kinetic energy. Momentum is a vector, so the direction of the velocity vector is of importance, too. Therefore, because 2 cars drive in 2 different directions, their momenta are different. b) is correct.