1. The kinetic energy is Ek = 0.5mv^2.
Ek = 1 J
m = 1 kg,
0.5 * 1 * v^2 = 1
v^2 = 2
v =sqrt (2) = 1.4 m/s
The velocity is about 1.4 m/s to have kinetic energy of 1 J for a 1-kg object.
2. When he is at the top of the slope, his kinetic energy is ...
The solutions provides an example of working with loss of potential energy when the man skies down the slope.