Final answer:
The kinetic energy of an 80kg man walking at a speed of 3 m/s is 360 joules.
Step-by-step explanation:
**Kinetic energy** is the energy possessed by an object due to its motion. The formula to calculate kinetic energy is:
Kinetic Energy = 1/2 x mass x velocity^2
In this case, the mass of the man is 80 kg and his velocity is 3 m/s. Plugging these values into the formula, we get:
Kinetic Energy = 1/2 x 80 kg x (3 m/s)^2 = 360 J
Therefore, the man's kinetic energy is 360 joules.