Hello,
http://fm92-1.com/physics.jpg"
The initial speed is 0 m/s
We let go of the rope
What is the system's kinetic energy when the little block is at 15 cm from the ground?
What's wrong with my work?
E_{t}=E_{P}+E_{F}+E_{K}\Rightarrow E_{K}=E_{t}-E_{P}-E_{F}
where Et is total energy...