Energy: What you get when you eat a whole bag of Skittles and six Mountain Dews? Not exactly. What IS energy? Let's find out!
So remember, energy is never actually LOST--it is just transferred or converted into other TYPES of energy. To go a little further into what potential and kinetic energy actually are, let’s watch this video! It may be an old cartoon, but the reality of energy has not changed!
Dropping a ball (or anything, really!)
Take a moment to think of a few more examples. When have you seen potential energy? When have you seen kinetic energy?
Let’s demonstrate this!
YOU WILL NEED:
- Tennis ball
- Tape measure or yard stick
Hypothesize: Does the height from which a ball is dropped affect how high a ball will bounce?
Here's what to do!
- Use the tape measure or yard stick to measure three feet up from the ground.
- Lift the basketball to the three foot mark.
- Drop the ball and pay attention to how it bounced. Record the height. Do this three times and find the average height.
- Now, measure five feet up from the ground. Repeat steps 1-3.
- Did the height from which the ball was dropped affect the height that the ball bounced? Explain.
Now, we will do the same with a tennis ball.
Hypothesize: Does the size of the ball affect how high it will bounce?
Repeat steps 1-5 with the tennis ball.
Did you get the same results? Explain.
Let's try something new! First, hold the basketball. Next, hold the tennis ball in place directly on top of the basketball. Drop both balls at the same exact time and watch what happens!
You should have seen the basketball hit the ground and the tennis ball hit the basketball, which then sends the tennis ball flying! When does the tennis ball bounce higher--on its own, or when it hits the basketball? Record your observations.
Why did the basketball cause the tennis ball to come bouncing back up? Would this work the same way if you dropped the balls in the opposite order? If you’re not sure, try it out and see what happens!
Based on your previous observations, which ball has more kinetic energy, the tennis ball or the basketball? Why do you think this is?
When you dropped the tennis ball and the basketball, you saw two forces at work. First, both the tennis ball and the basketball had a force acting upon them--gravity. Second, when the basketball hit the ground, the energy from the impact was transferred to the tennis ball, creating contact force.
What is force, you ask? Force is the push or pull of an object that happens when an interaction between two objects occur. Picture two vehicles crashing into each head on at the same speed. If one vehicle is a semi-truck and one is a Mini Cooper, which vehicle will have more force enacted upon it? Well, think of the tennis ball as the Mini Cooper and the basketball as the semi-truck. That’s just a start on understanding force and Newton’s Laws, but that's enough for now!
Until next time--May the force be with you!
Image and Video Credits, in order of appearance:
The Science Asylum, 2013. What is Energy REALLY?! Uploaded from YouTube on 9/4/2016. https://youtu.be/jCrOtF7T4HE
cassiw2, 2009. The story of potential and kinetic energy. Uploaded from YouTube on 9/4/2016. https://youtu.be/7K4V0NvUxRg
Bartz & Maggs, 2007. Bouncing ball strobe edit. Uploaded from Wikimedia Commons on 9/4/2016.
https://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/Bouncing_ball_strobe_edit.jpg/1024px-Bouncing_ball_strobe_edit.jpg File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made.
Psalter, 1324. Longbowmen. Uploaded from Wikimedia Commons on 9/4/2016.
https://upload.wikimedia.org/wikipedia/commons/a/a7/Longbowmen.jpg File released into the Public Domain.
BrandonR, 2005. Wooden roller coaster txgi.
Uploaded from Wikimedia Commons on 9/4/2016. File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made.
Utchay Endre, 2008. May the force be with you. https://youtu.be/vSJNeXrCbE4 Uploaded from YouTube on 9/4/2016.