Balancing Stick
Learn how to balance a stick using the centre of mass!
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual outreach to youth.
What To Do
- Place a pipe cleaner 2-3 cm from the bottom of the popsicle stick.
- Twist the pipe cleaner around the popsicle stick. Make sure the pipe cleaner is the same length at both sides of the popsicle stick.
- Angle each side of the pipe cleaner down like a triangle.
- Clip a clothespin to one end of the pipe cleaner.
- Clip a clothespin to the other end of the pipe cleaner.
- Hold the bottom of the popsicle stick with one finger (see photo in guide). Does the stick balance on your finger?
It may take a few tries before students are able to balance the stick on their finger. If they are having trouble, they can adjust the pipe cleaner and try again.
Discovery
When you are trying to balance any object, there will be one point of the object where you can hold it so it balances perfectly. This is called the centre of mass. This special point is where the object won't tip to the left or right and will stay put in one place.
Your body has a centre of mass too! When you are standing still, your centre of mass is right above your belly button. But if you are only standing on one leg, your centre of mass will change! If you stand on your right leg, your centre of mass will move slightly to the right side of your belly button. The same thing happens when you stand on your left leg- your centre of mass will move slightly to the left side of your belly button.
Do some experimenting!
- Remove one clothespin- does it still balance?
- Hang some elastics on one clothespin and try to balance the stick- what happens?
Guide:
What's Happening?
When you are trying to balance any object, there will be one point of the object where you can hold it so it balances perfectly. This is called the centre of mass. This special point is where the object won't tip to the left or right and will stay put in one place.
Your body has a centre of mass too! When you are standing still, your centre of mass is right above your belly button. But if you are only standing on one leg, your centre of mass will change! If you stand on your right leg, your centre of mass will move slightly to the right side of your belly button. The same thing happens when you stand on your left leg- your centre of mass will move slightly to the left side of your belly button.
Investigate Further
Do some experimenting!
- Remove one clothespin- does it still balance?
- Hang some elastics on one clothespin and try to balance the stick- what happens?