Translational Kinetic Energy

When you have any mass, m, at any speed, v, its kinetic energy is…

Unit of kinetic energy?

Joules (J)

1 Joule =

Kinetic energy is always _____ and it is a ____.

positive, scalar

Sketch K(v)

System

a portion of the universe chosen for analysis

Kinetic energy of a system?

The sum of kinetic energy of each of its parts

We ____ use center of mass for kinetic energy of a system

CAN’T

Does kinetic energy depend or not depend on frames of reference?

It depends.

Does kinetic energy depend on the angle of velocity?

No, it is a scalar.

Kinetic energy’s value ____ on direction of motion but only the _____ at a given instant.

does not depend, magnitude of the velocity

How does the kinetic energy of a falling object change when air resistance is present?

As the object falls, air resistance increases, so the net force and acceleration decrease. Since acceleration is the slope of the velocity-time graph, a decreasing acceleration means the velocity graph’s slope gets smaller. Therefore, velocity is still increasing, but at a decreasing rate. Since K= 0.5mv², kinetic energy also increases at a decreasing rate until terminal velocity, when acceleration is zero and both velocity and kinetic energy become constant.

When is a block’s kinetic energy greatest as it compresses a spring while sliding down a frictionless incline?