An object traveling at 5 m/s is known to have a kinetic energy of 100 J. What would its kinetic energy be...?

when it is traveling at 10 m/s? Explain your reasoning.

mv^2/2 = 100 J
v = 5
m * 25 = 200J
m = 8 kg

8 * 10^2/2 = 400 J

Or you can think it directly. If you double the speed, the energy gets four times higher, since it's v^2.

K.E = 0.5 x mass x velocity x velocity

i.e. 100=0.5 x 25 x mass
therefore, mass= 4/0.5
= 8 kg

when velocity = 10m/s,

KE = 0.5 x 10 x 10 x 8
= 50 x 8
= 400J