# An object has a mass of #6# #kg#. The object's kinetic energy uniformly changes from #88# #kJ# to # 48# #kJ# over #t in [0, 6 s]#. What is the average speed of the object?

##### 1 Answer

Mar 23, 2016

From the kinetic energy and the mass given, the initial speed is

#### Explanation:

I don't think we actually need to know the time taken. Let's find out.

We know

That means the initial speed (we don't care about direction) is:

The final speed is:

Since the object is decelerating uniformly, the average speed will just be:

Whether it decelerated over 1, 2 or 6 seconds, the average speed would be the same.