Calculating Kinetic and Potential Energy of a Moving Object

[Chemicist]

Thanks for correcting me ehild!

 

[ehild]

The solution is almost correct, Janed. But it is convenient to take the potential energy zero at the ground.

Ok I tried redoing the whole problem...

KE= 36.125 J
PE = 0 J

The ball was kicked from 1.5 m, so the initial potential energy is (0.250) (9.81) (1.50) instead of zero.
Your way of solution is correct otherwise, just correct the total energy according to the initial potential energy.

ehild

 

[ehild]

ya if an object is moving means it does not have any P.E energy

It is wrong, Thinkhigh. When you drop a stone, for example, the velocity increases with time t as v=gt, and its height decreases as h=h₀-0.5gt². The potential energy with respect to the ground is PE=mgh, The kinetic energy is KE=0.5mv². The PE continuously transforms into KE. Substituting v=gt and h=h₀-0.5gt² into the equations for PE and KE, the total energy is

E=0.5mg²t²+mg(h₀-0.5g²t²)=mgh₀, constant, equal to the initial PE.

ehild