Question

15. A volleyball player who weighs 650 Newtons jumps 0.500 meters vertically off the floor. What is her kinetic energy just before hitting the floor?

Answer 1

Kinetic energy just before hitting the floor is 324.57 J

Explanation:

Weight of volleyball player = 650 N

That is

            Mass x Acceleration due to gravity = 650

            Mass x 9.81 = 650

            Mass = 66.26 kg

We also have equation of motion v² = u² + 2as

Initial velocity, u = 0 m/s  

Acceleration, a = 9.81 m/s²  

Final velocity, v = ?

Displacement, s = 0.5 m

Substituting  

v² = u² + 2as

v² = 0² + 2 x 9.81 x 0.5

v = 3.13 m/s

Velocity with which he lands on ground is 3.13 m/s

We have kinetic energy = 0.5 x Mass x Velocity²

Substituting

          Kinetic energy = 0.5 x 66.26 x 3.13²

           Kinetic energy = 324.57 J

Kinetic energy just before hitting the floor is 324.57 J