Your friend says that the KE of an object depends on the reference frame of the observer. Explain why you agree or disagree.

The energy possesed by virtue of motion of the body is called its kinetic energy. The formula for the kinetic energy is given by

K. E. = 1/2 mv²

Here, m is the mass of the body and v be the velocity of the body.

As the velocity of the body depends on the frame of reference so the kinetic energy also depends on the frame of reference.