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

2 Answers
Mar 14, 2018

#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"#

Mar 14, 2018

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!