The figure below shows the potential energy for an object moving in response to
ID: 1477442 • Letter: T
Question
The figure below shows the potential energy for an object moving in response to conservative forces from a number of other objects that can be treated as fixed, so we can pretend this is the PE of a single object. Never mind the units of either position or PE for now. We can think of this as about a skateboarder rolling back and forth on a curved track.
A. Suppose the skateboarder starts with 0 kinetic energy at the point ?5 and starts to roll. Describe the motion she will go through assuming that whatever resistive forces are acting can be neglected. Describe one full cycle of the motion.
B. The PE curve is shown as going to negative values. Is this a problem? Explain.
Explanation / Answer
Work done by a conservative force can be expressed as negative gradient of potential energy.
we know that gravitational force is a conservative force.
A.as the skareboarder starts with 0 kinetic energy at point - 5 , total energy is potential energy
potential energy is gradually converts in to kinetic energy, as skater reaches the bottom the potential energy minimum,
and kinetic energy is gradually converts into potential energy (increasing), becomes maximum at top (0) ,skater may not stop at that position
so that it repeats again .
B. potential energy is negative when the object moving down ward and the skater moves upward the p.e is positive here the value is increasing.