How High Does a Basketball Bounce After Losing 20% Energy?

[aleferesco]

Homework Statement

A basketball is dropped from a height of 2m. It lost lost 20% of its energy, in the bouncing from the floor due to friction in the air, before it reaches the highest point of its first bouncing. How high did it bounce?

h1= 2m
h2=?
g=9.8m/s^2

Homework Equations

PE = mgh and Energy Total (initial)=Energy Total (final)

mgh1 = 0.20 + mgh2

The Attempt at a Solution

I don't know how to solve it without the mass and kinetic energy

 

[PhanthomJay]

Homework Statement

A basketball is dropped from a height of 2m. It lost lost 20% of its energy, in the bouncing from the floor due to friction in the air, before it reaches the highest point of its first bouncing. How high did it bounce?

h1= 2m
h2=?
g=9.8m/s^2

Homework Equations

PE = mgh and Energy Total (initial)=Energy Total (final)

mgh1 = 0.20(?)[/color] + mgh2

check this equation for an error...20% of what?

The Attempt at a Solution

I don't know how to solve it without the mass and kinetic energy

What's the initial KE at the release point? What's the final KE at the top of the first bounce?