Here is a problem I am having some trouble with:
The solution is below, my question is, why is conservation of energy valid in this situation.
From my understanding, just before the box hits the springs, energy is conserved since its just gravity. BUT, when the box hits the springs, THERE IS A NORMAL FORCE.
Why don't they take the normal force into account? Its in opposite direction of the motion.
The force of gravity and springs are taken into account as potential energy ,am I right here?
Please answer both questions.