Posted by Peter on .
A large airfilled 0.1kg plastic ball is thrown up into the air with an initial speed of 16 m/s. At a height of 4.7 m, the ball's speed is 5 m/s. What fraction of its original energy has been lost to air friction? (Note that the initial height is taken to be zero.)

Physics 
drwls,
Initial energy = (M/2)*Vo^2 = 12.80 J
Total energy at 4.7 m and V = 5 m/s:
= (M/2)*5^2 + M*g*4.7 = 1.25 + 4.61 J
Fraction of ball's energy LOST = (12.805.86)/12.80
= 0.542