If an object with a mass of #5 kg # changes speed from #5m/s# to #10 m/s#, by how much does its kinetic energy change?

1 Answer
Mar 25, 2018

Answer:

The object has gained #375 \ "J"# of kinetic energy.

Explanation:

The initial kinetic energy is:

#"KE"_1=mv_1^2#

  • #m# is the mass of the object in kilograms

  • #v_1# is the initial velocity, which is #5 \ "m/s"#.

And so, we get,

#"KE"_1=5 \ "kg"*(5 \ "m/s")^2#

#=5 \ "kg"*25 \ "m"^2"/s"^2#

#=125 \ "J"#

The final kinetic energy is:

#"KE"_2=mv_2^2#

  • #v_2# is the final velocity, which is #10 \ "m/s"#.

Again, we just plug in values into the equation, and we get,

#"KE"_2=5 \ "kg"*(10 \ "m/s")^2#

#=5 \ "kg"*100 \ "m"^2"/s"^2#

#=500 \ "J"#

The change in kinetic energy is:

#Delta"KE"="KE"_2-"KE"_1#

#=500 \ "J"-125 \ "J"#

#=375 \ "J"#