Imagine you are on a merry-go-round at the park. What makes it move? Imagine you are on a carousel? What makes it move? Imagine you are on the Gravitron at a fair (that ride that makes you stick to the sides of the chamber). What makes it move? What do you think is required to move objects? What do you think makes a motor run?
Student Guide
Magnetic Merry-Go-Round
Experimenting with motors
How can you make a merry-go-round turn without pushing it?
This resource was originally published in PhysicsQuest 2016: Currents.
How can you make a merry-go-round turn without pushing it?
- AA battery
- Nail
- Mini umbrellas
- Magnet
- Insulated wire
- Tape
- Paper clip
- Cup of water
- Small piece of styrofoam
Intro
Before the experiment
What types of motors can you think of? What do they have in common?
Setting up
First you need to figure out which is the north side of your magnet and which is the south side.
Embed the magnet in the small piece of styrofoam and float it in the cup of water. If you can’t find styrofoam, you can use any material that floats and can hold the magnet.
It should immediately align with the Earth’s magnetic field and one flat side will face north while the other faces south.
The side of the magnet facing south is the side of the magnet attracted to the magnetic south. Since north is attracted to south, this means it’s the north side of the magnet. Use a marker to label it with an “N.”
Push the stick through the top of the mini umbrella so you have just the top of the umbrella with a hole in the middle.
Stick the paper clip through the hole and bend the bottom so the umbrella top is hanging off the paper clip.
Put the magnet on the head of the nail with the “N” side against the head.
Hang the paper clip/umbrella top contraption off the other side of the magnet.
The nail will now be magnetic thanks to the magnet. Hang the nail by its point from the negative side of the battery.
Hold the battery so the nail is hanging and free to move.
During the experiment
Put the south end of the magnet against the head of the nail.
Draw your setup, indicating where the north and south ends of the magnet are as well as the positive and negative ends of the battery.
Now touch the wire to both the positive end of the battery and the side of the magnet. What happens?
Now hang the magnet and nail from the positive end of the battery and touch the wire to the negative end and the side of the magnet. What happened? How does this compare to what happened before?
Repeat steps 2-3 with the north side of the magnet against the head of the nail.
Analyzing data
Draw the two setups that made the pinwheel turn clockwise.
Draw the two setups that made the pinwheel turn counterclockwise.
Conclusion
Draw a mechanism (model, picture, diagram, sketch) for what you think is happening INSIDE the magnet, nail, paperclip, and umbrella as it spins.