# An object has a mass of #4 kg#. The object's kinetic energy uniformly changes from #12 KJ# to # 72KJ# over #t in [0,5s]#. What is the average speed of the object?

##### 2 Answers

#### 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

#### Answer:

133.63 m/s

#### Explanation:

Using equation of kinetic energy, i.e E =

We get initial velocity=u was 77.46 m/sec and final velocity=v was 189.73 m/sec

Now,using v=u+at(all symbols are bearing their conventional meaning) we get a is 22.45

Hence putting it in

We get total distance covered in 5 sec is 668.152 meter.

So, average speed = (total distance covered/total time) =