If an object with a mass of #7 kg # changes speed from #4ms^-1# to # 5 ms^-1#, by how much does its kinetic energy change?

1 Answer
Jan 14, 2016

Answer:

The kinetic energy changes from #56 J# to #87.5 J#, a change of #31.5 J#.

Explanation:

Kinetic energy is given by #E_k = 1/2mv^2#

If the mass, #m#, is #7 kg#, and the velocity, #v#, is #4 ms^-1#, the #E_k# is #56 J#. If the velocity changes to #5 ms^-1# the #E_k# changes to #87.5 J#. Subtracting the former from the latter gives a change of #31.5 J#.