Answer: 100 joules
Step-by-step explanation:
Given that
Mass of rock = 0.5-kg
Velocity = 20 m/s
Kinetic energy = ?
Kinetic energy is the energy possessed by a moving object, and it depends on its mass and velocity.
Thus, K.E = 1/2 x Mass x (velocity)^2
K.E = 1/2 x 0.5kg x (20m/s)^2
K.E = 0.5 x 0.5 x 400
K.E = 100 J
Thus, the kinetic energy of the rock is 100 joules.