# An object has a mass of #9 kg#. The object's kinetic energy uniformly changes from #54 KJ# to # 45 KJ# over #t in [0, 4 s]#. What is the average speed of the object?

##### 1 Answer

#### Answer:

The average speed is

#### Explanation:

The kinetic energy is

The mass is

The initial velocity is

The final velocity is

The initial kinetic energy is

The final kinetic energy is

Therefore,

and,

The graph of

The points are

The equation of the line is

So,

We need to calculate the average value of

So,

The average speed is