Answer:
19.98Joules
Step-by-step explanation:
Energy possessed by the body is the kinetic energy
Kinetic Energy = 1/2mv²
m is the mass
v is the velocity
For the 4kg moving at 6m/s
kE = 1/2 * 4 * 6^2
KE = 1/2 * 4 * 36
KE = 72Joules
For the 4kg moving at 5.1m/s
kE = 1/2 * 4 * 5.1^2
KE = 1/2 * 4 *26.01
KE = 52.02Joules
Amount of Energy lost = 72 - 52.02
Amount of Energy lost = 19.98Joules
Hence the amount of Energy lost is 19.98Joules