Question

Two objects with the same mass and same speed, but moving in opposite directions, have the same kinetic energy. Explain why this is true. A. Kinetic energy changes as an object falls in a gravitational field. B. Kinetic energy has units of joules. C. Kinetic energy is a scalar quantity that depends only on the speed but not direction of velocity. D. It is false. The two objects have opposite kinetic energies

Answer 1

We are given that two objects of same mass have the same velocity but in opposite directions. The kinetic energy of each object is given by:

$K=\frac{1}{2}mv^2$

Where:

$\begin{gathered} m=\text{ mass} \\ v=\text{ magnitude of velocity} \end{gathered}$

Since the kinetic energy depends on the mass and the magnitude of the velocity, this means that the object will have the same kinetic energy regardless of the direction of the velocity. Therefore, option C is correct.