SAT Physics Subject Test

Chapter 4 Work, Energy, and Power

KINETIC ENERGY

Consider an object at rest (v0 = 0), and imagine that a steady force is exerted on it, causing it to accelerate. Let’s be more specific; let’s say that the object’s mass is m, and let F be the force acting on the object, pushing it in a straight line. The object’s acceleration is a = F/m, so after the object has traveled a distance ∆s under the action of this force, its final speed, v, is given by Big Five #5:

But the quantity Fs is the work done by the force, so W = mv2. The work done on the object has transferred energy to it, in the amount mv2.


The energy an object possesses by virtue of its motion is therefore defined as mv2 and is called kinetic energy.

K = mv2