# The kinetic energy of an object with a mass of #5 kg# constantly changes from #72 J# to #480 J# over #12 s#. What is the impulse on the object at #2 s#?

##### 1 Answer

#### Answer:

Assume that the kinetic energy is increasing at a constant rate. After 2s, the impulse on the object would have been

#### Explanation:

The impulse exerted on an object equals the change it in its momentum

The object's initial kinetic energy is 72 J, so

To find the impulse on the object at 2s we need to find the speed of the object,

We are told that the kinetic energy changes constantly. The kinetic energy changes by

This means that the kinetic energy changes at a rate of:

In two seconds the kinetic energy will have increased by

Therefore, at 2s the kinetic energy is

Now we have to make sure

Substitute