It is recommended that you try these simple yet effective activities and experiments at home to help you get a better idea of the various forms of potential energy. You can explore Energy Forms, Simple Machines, or how energy is measured and quantified. If you are an educator, these experiments can be used in the classroom. Have fun!
A simple way to demonstrate elastic energy is to stretch a rubber band and not let go, the stretch demonstrates potential energy. Let go of the rubber aiming it toward a wall and it is converted to kinetic energy.
The rubber band can also illustrate energy conversion. Place the band against your upper lip to measure its temperature. Stretch and release the band repeatedly. Test the temperature again. It should feel warmer.
Why does it feel warmer and where do you think the heat energy came from?
To demonstrate gravitational potential energy, hold a basketball over your head and release it on to the pavement. Gravity pulls the ball towards the Earth creating kinetic energy as it drops until it hits the pavement converting it back to potential. This conversion from potential to kinetic is repeated as the ball bounces up and down the pavement.
When you drop the ball, note how high it bounces back. Why doesn’t it bounce back to the same height at which you let it go? If you let the ball keep bouncing, notice that with it bounces back a little lower each time.
If the ball were to bounce back to the same height at which it was dropped, that would mean all the gravitational energy was converted to kinetic energy. It isn’t all movement, though is it? Listen (that’s a hint), what other forms of energy can you detect or identify? Think back, too, to the rubber band experiment–can you think of another energy form?
Check out SnapShot Science’s ball bouncing experiment!
Note: Using a clear soda bottle helps to demonstrate what is happening inside.
Punch a hole through the lid and the bottom of the container. Take the lid off the container. Thread a string through the bottom of the container and pull it through the lidless top of the container (make sure there is still string hanging out the bottom end).
Tie the end of the string that you pulled through the top to one end of the rubber band (you will use the string as a lead to help thread the rubber band through the container).
Tape the washers together and then connect them to the middle of one section of the rubber band (do not tape the strands of the rubber band together).
Put the end of the rubber band (the end not connected to the string) through the container lid. Use a toothpick to secure the band so that it does not slip inside the container (put the toothpick through the end loop of the rubber band that remains outside the hole). Put the lid on the container (making sure the string is still sticking out the other end).
Carefully pull on the thread until the rubber band comes through the hole. Secure the band with the second tooth pick. Be sure to situate the weight so it is in the center of the container and does not touch the sides. Your roll-back toy is ready to go!
Roll the toy and watch as the weight holds one strand of the rubber band stationary while the free side twists around. The farther the toy is rolled the more potential energy. Release and watch the toy roll back towards you demonstrating kinetic energy. This would be a great activity to have races in the classroom to see who could devise the roll-back toy with the greatest potential energy.
Check out this Physics Project: Rollback Can
Note: Only attempt this activity where this is overhead space and room to move away.
Pour a 1/2 cup of water and a 1/2 cup of vinegar into the flask. Put a spoonful of baking soda into a coffee filter, roll and twist it closed. Put the coffee filter in the flask, cork it and move away…fast! Both the baking soda and vinegar contain molecules (which have potential energy in their bonds). When mixed together the bonds break and the molecules rearrange themselves to produce a gas releasing energy. The continued production of gas in a closed container increases the pressure (potential energy) in the container. This experiment demonstrates chemical energy converted to mechanical energy or movement.
Design an EMPTY film canister (or non-childproof prescription bottle, candy tube, glue stick) to look like a rocket (add fins, nose cones, etc.). Put a little baking soda and vinegar in the rocket and quickly close the lid and invert. Lift off! (NOTE: You’ll need to use the type of canister where the lid fits inside the canister rather than the cap style.)
Simply pour a small amount of vinegar onto baking soda causing a chemical reaction. Again, when mixed together the bonds break and the molecules rearrange themselves releasing energy. (Taken from “Potentially Kinetic,” KEEP Energy Education Activity Guide.)
Chemical and electric potential energy can be demonstrated through a battery in a flashlight. In batteries chemicals are used to separate electrons (- charge) from protons (+ charge), momentarily moving them. The separated positive and negative electric charges of a battery represent another form of potential energy called electric potential energy. When a battery is connected to an electrical circuit (such as a flashlight being turned on), the electrons leave the negative terminal of the battery and move (flow) through the circuit to the positive terminal.
In energy terms, electrical potential energy in the battery is converted into kinetic energy of moving electrons. Think back to the waterfall analogy used to discuss voltage and current. The voltage is the height of the water fall and the current is the falling water (flowing electrons). The electrons’ kinetic energy is then converted into another form, such as light with the flashlight. (taken from “Potentially Kinetic More About Batteries,” KEEP Energy Education Activity Guide.)
Sound is caused by vibrations that moves air molecules in waves. To demonstrate that sound waves move through the air cover a bowl with plastic wrap and secure it with a rubber band. Sprinkle salt over the plastic wrap. Over the bowl with sprinkled salt clang a metal pot with a spatula. The sound vibrations from the clanging will cause the air molecules to move causing the salt on the plastic wrap to move.
Sprinkle the rice on a plate and place it on top of a stereo speaker. Turn the music on (preferably a song with a loud bass). Watch the rice dance!
Sound travels faster through metal and brick than it does in air. To demonstrate this, find a brick or metal building. Have one student place one ear on the building.
The student with his or her ear on the building should hear the message in the ear placed on the building first before he hears it with the air exposed ear.
Sound waves bounce off objects obstructing them causing an echo. To demonstrate that objects obstruct sound waves roll up a piece paper and hold the one side to your ear. Have someone stand behind you and hit two spoons together behind your left ear, your right ear, and above your head. The ear that has the paper held up to it will not be able to pick up the sound waves from the spoons being tapped above your head, so you will think it is coming from behind the unobstructed instead.
First place a metal spoon in the water for a few minutes, then feel the end sticking out of the saucepan. It should feel warm because of conduction. Next, place all the spoons made from different materials in the saucepan. After a few minutes, touch the handle tips of each spoon and determine which is the hottest and why. Students can arrange spoons from best to worst conductors and discuss why (Taken from “Exploring Heat,”KEEP Energy Education Activity Guide.)
Cut a spiral or coil out of the piece of paper and tie a string to the end of the spiral. Hold the coil above the heat source. The heated air moving by the process of convection will cause the paper to spiral.
Caution: Incandescent light bulbs get very hot. If you are using a candle, hold the coil and make sure the paper does not touch the flame. (Taken from “Exploring Heat,” KEEP Energy Education Activity Guide.)
Put a balloon over the top of an empty ketchup bottle (you may need to put a rock in the bottom of the bottle for weight). Place the bottle in a saucepan of hot water. The balloon should expand because the air inside the bottle gains thermal energy and the molecules move around more, filling the space inside the balloon. (Note: If this experiment is performed in the classroom, the teacher should place the bottle in the water as it gets very hot. (Taken from “Exploring Heat,” KEEP Energy Education Activity Guide.)
Dip the penny and the threads of the bottle neck in the cold water. Put the penny over the opening of the bottle and wrap hands around the bottle until the penny jumps. The heat from your hands is transferred through conduction to the air in the bottle warming the air. This causes the air molecules to move faster which makes the penny jump.
The main understanding for students to achieve during simple machines unit is that the tools change the direction of a force. Machines change the state of energy to produce work. Work is force multiplied by distance. Another way of saying this is that humans use their energy with simple machines to do work by changing the state of energy of the object (system) they’re working on (e.g., from potential to kinetic).
The result of simple machines is that the same amount of energy is transferred (used), but because the effort is less it is often confused with using less energy. Machines make the effort easier for humans, but the same amount of work is done. Simple machines also make work easier because they use less power (i.e., they are faster and require less time; they increase the speed at which the work is done). Students might have heard the term “powerful” used with certain automobiles. It is powerful because the engine allows the car to increase from 0 to 60 mph in less time.
It might be too difficult to introduce the role of energy in a Simple Machines unit; however, the following challenge could help students consider energy transfer when examining how simple machines “work”. The main objective of this exercise is to help students who equate energy with effort or with force and this is not a scientifically accurate use of the term energy. Of course, in everyday language, these applications are acceptable.
A person is directed to put a heavy box that is on rollers onto the back of a truck. She can lift the box to the truck, use a steep ramp, or a ramp that is less steep.
Students can simulate the challenge by securing a weight (such as a book or a paperweight) to a large toy car or truck. Tie a rope around the truck and weight. Tell students they are to move the truck and weight from the ground to the top of a box (they should pull the object by the rope). Provide students with different length boards to serve as ramps (steep and gentle slopes). Have students use a spring scale to measure the differences in force among the various options.