Question

What is the kinetic energy of an object that has a mass of 30 kilograms and moves with a velocity of 20 m/s?

Answer 1

`6000 \ "J"=6 \ "kJ"`

Explanation:

Kinetic energy of an object is given by the equation

`"KE"=1/2mv^2`

where `m` is the mass of the object in kilograms, `v` is the velocity of the object in meters per second.

So, plugging in our given values into the equation, we get

`"KE"=1/2*30 \ "kg"*(20 \ "m/s")^2`

`=1/2*30 \ "kg"*400 \ "m"^2"/s"^2`

`=15 \ "kg"*400 \ "m"^2"/s"^2`

`=6000 \ "kg m"^2 \ "s"^2`

Now, we know that `1 \ "J"=1 \ "kg m"^2 \ "s"^2`, and so we got:

`=6000 \ "J"`

Also, we can convert it to kilojoules by dividing by one thousand, and so we have:

`=6 \ "kJ"`

Answer 2

6000 Joules

Explanation:

`KE=1/2mv^2`

`KE=1/2(30)(20)^2`

`KE=15*400`

`KE=6000J`

For this formula, always use kilograms as your unit of mass and m/s for your unit of velocity. This will yield a unit of Joules.

Don't forget your units!