Today we did a pre-lab discussion for the two remaining energy assets, kinetic and gravitational. The discussion centered around how we could use the knowledge we have of elastic energy to study kinetic and gravitational energy. It was an easy discussion because most of the students saw pretty quickly that we could use a spring to launch a cart. To study the kinetic asset, we just need to choose the initial condition (for the energy bar graphs) when the spring has been compressed but the cart is at rest, and the exact instant the spring is no longer compressed (so all the elastic is now kinetic) for the final condition. For the gravitational, just launch the cart up a ramp, and use the maximum height as the final conditional so all the energy is gravitational.
We have two main springs to use to launch the carts. The first is the one built into out Pascar’s. The second is the launcher available from Pasco that looks like this:
Both experiments start with a quick Hooke’s Law experiment to create the Force vs. change in length graph and or (depending on how the group chooses to quantify the energy). I helped each group use a WDSS Fore sensor and Motion detector at the same time to directly create the ‘Hooke’s Law’ Graph.
Having just discussed N2L, and using the Giant Lab Cart of Physics, we turned to connecting N2L to N1L and N3L. We accomplished this by using our two giant hovercrafts of physics:
The two examples had the same series of questions… 1. Which person exerted the greater force ? Explain, 2. Which person had the greater acceleration? Explain, and 3. Which person has the greater velocity after the interaction.