A truck has four times the mass of a car and is moving with twice the speed of the car. If K_t and K_c refer to the kinetic energies of truck and car respectively, it is correct to say that A) K_t = 16K_c. B) K_t = 4K_c. C) K_t = 2K_c. D) K_t = K_c. E) K_t = $\frac { 1 } { 2 }$ Kc.

Question

Quizplus · Accepted Answer

The kinetic energy is given by $ K = \frac{1}{2}mv^2 $. If the truck has four times the mass (4m) and twice the speed (2v) of the car, then its kinetic energy is $ \frac{1}{2}(4m)(2v)^2 = 16(\frac{1}{2}mv^2) $, which is 16 times the kinetic energy of the car.

A Truck Has Four Times the Mass of a Car 12\frac { 1 } { 2 }21​

A Truck Has Four Times the Mass of a Car $\frac { 1 } { 2 }$