Question

The potential energy stored in a spring depends on how much it is stretched. Suppose we have a box attached to the same string, but now the other end of the spring is fastened on the floor. Initially, the box sits on the floor, so that the potential energy of the spring is zero. If the box is now is thrown upward with some initial kinetic energy, but its upward speed goes to zero at the height h of the shelf. what was its initial kinetic energy? a. mgh b. 2 mgh c. 3 mgh d. 4 mgh e. there is not enough information given in the problem to tell

          The potential energy stored in a spring depends on how much it is stretched.  Suppose we have a box attached to the same string, but now the other end of the spring is fastened on the floor.  Initially, the box sits on the floor, so that the potential energy of the spring is zero.  If the box is now is thrown upward with some initial kinetic energy, but its upward speed goes to zero at the height h of the shelf.  what was its initial kinetic energy?
a.  mgh
b. 2 mgh
c.  3 mgh
d. 4 mgh
e.  there is not enough information given in the problem to tell

Added by Hien T.

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