We have a mass of 200g (0.2kg) moving at 20m/s
Kinetic Energy KE = ½ mv^2 where m is mass and v is velocity
Actually, v is a vector quantity, so KE = ½ mv•v
The dot product of 2 vectors a and b is abCosθ where θ is the angle between the vectors.
Obviously v•v = v^2 Cos0 = v^2
In this case, we have KE = ½ (0.2)(20^2) = 40kg-m^2/s^2 = 40J
So we have kinetic energy in the amount of 40 Joules.
