Today we used a tennis ball and rolled it down a ramp to learn about the different types of energy being involved.

Today I learned:

There are many types of energy affecting a simple ball and ramp. Kinetic energy is energy that comes from the movement of an object. The heavier and faster that object, the more kinetic energy. It is demonstrated when the ball rolls - the ball has kinetic energy from the movement. Gravitational potential energy is energy that comes from the ‘lifting’ of an object. The higher an object goes, the more potential there is for gravity to affect it, and therefore it has more potential energy. When the ball rolls up the incline, at the top it has a lot of graviational potential energy and it is able to release it when it rolls back down the hill. Remember: at the top, gravity has the potential to bring something down with a lot of force.

There are many different diagrams that can be used to represent the energies that are involved in a system (objects with properties that we keep track of). First is the energy flow diagram: it consists of a circle with all the elements of the system inside, and arrows that show the flow of energy in and out of the system. This represents external work. Internal energy transformations are not shown. The second is the energy storage diagram: it has two bar graphs that show the amount of each type of energy stored at two different points of time. Usually, there is a an energy flow diagram inbetween the two bar graphs, which represent the energy transformations. It creates a LOL diagram.

Energy change of a system due to a force is ‘work’. When force is the same direction as displacement, W = FΔd. GP energy of object with mass m at y units above a reference is Eg = mgy or GP energy = mass x gravity x height. Units for energy are Newtons x metres, which are called ‘Joules’. These are measured in kgm^2/s^2.

Today I wondered:

Is it always true that gravitational potential energy always goes up when an object is elevated? How high is this maximum or is there a maximum?

Why is the energy increase/decrease (change) called work? What meaning does this have?

Today I had an intriguing idea:

The GP energy, kinetic and other energies for an object on a roller coaster loop should be similar to the one for an an incline up and down, as the roller coaster is just going up, then coming back down albeit in a slightly loop fashion.

After Unit Reflection

This post connects to #5d and #5e. It demonstrates an understanding of kinetic and gravitational potential energy through the ball and ramp lab. When the ball rolls down the ramp, it is a very simple and easy to understand yet extremely clear example of what kinetic and GP energy is. GP energy is demonstrated when bringing the ball to the top of the ramp. Of course, the energy is not visible to the eye. However, we can see the kinetic energy as the ball rolls down the ramp. The kinetic energy is motion, so we can see what that is. But where did that energy come from? It must have come from somewhere, as no new energy is created or destroyed. The answer would be GP energy, which is due to the force of the earth’s gravity.