Science Buddies: "Ask an Expert"

I am mentoring my 5th grade student with her first science fair project. We have some questions about when and how the marble acquires energy. Please help us to pinpoint this by helping us with the following understandings:

1. Is the marble gaining energy when it is being lifted by someone to the top of the slide or is this only the potential for acquiring energy at this point ( ie.. potential energy) ?

2. Is the marble gaining energy when it rolls down the slide once the person releases it? If so, is this acquisition of energy due to gravitational force?

3.Is the marble storing energy as well as gaining energy as it rolls down the slide? If so, at what point does this stored energy begin to transform into kinetic energy?---Is it transforming while rolling down or does this transformation take place at the bottom of the slide just prior to looping itself around the loops?

Hello and welcome to the forums

It sounds like you might want to review potential versus kinetic energy. You can find several good sources of information on the web, such as Wikipedia: http://en.wikipedia.org/wiki/Potential_energy

Here's a summary of Potential Energy:

Potential energy is often associated with restoring forces such as a spring or the force of gravity. The action of stretching the spring or lifting the mass is performed by an external force that works against the force field of the potential. This work is stored in the force field, which is said to be stored as potential energy. If the external force is removed the force field acts on the body to perform the work as it moves the body back to the initial position, reducing the stretch of the spring or causing a body to fall.

1. Yes, as you lift the marble (with kinetic energy) you increase the marble's potential energy.
2. When the marble drops, potential energy is converted into kinetic energy.
3. See 2. If the marble is closer to the earth, its potential energy is less and has been transformed into kinetic energy.

Best, Keith