Help pls it’s urgent giving brainiest!!

Consider a system with two masses that are moving away from each other. why will the kinetic energy differ if the frame of reference is a stationary observer or one of the masses?

In a system with only a single force acting upon a body, what is the relationship between the change in kinetic energy and the work done by the force? answers: work is equal to the change in kinetic energy.work depends on the square of the change in potential energy.work is equal to the negative of the change in kinetic energy.work is equal to the square of the change in kinetic energy

Macy always thought there were only a few hair colors blonde brown and black however when she actually began looking around she saw varying shades of these hair color what is a possible reason for so many different hair colors