To find the Kinetic energy this is the equation
KE=1/2mv^2
so we know the mass (m) which is 8kg
we also know the velocity (v) which is 10 m/s
so we plug that into the equation and it should look like this - 1/2(8kg)(10m/s)^2 now we solve
so 1/2 x 8 = 4 so then we just do (4)(10)^2 which gets us 400.
Since kinetic=Joules
The answer is 400 J