Hold the wine glass with both hands as shown and begin to swirl the ball inside the glass around and around.
Speed up the swirling pace and turn the wine glass on it’s side.
Start to move the wine glass rapidly back and forth to build up even more speed of the ball inside the glass. Now begin to tip the glass upside-down whilst still moving the glass rapidly.
You cannot slow down now!
Completely turn the wine glass upside-down whilst still moving the wine glass back and forth rapidly. If you’ve got it right, the ball will continue to speed around and around the glass without falling out!
Get the Unit of Work on Forces here!
- Push, pull
- Friction & spin!
From inertia to centripetal force, this unit covers many concepts about Newton’s Laws!
Includes cross-curricular teaching ideas, student quizzes, a sample marking rubric, scope & sequences & more
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What is going on?
This experiment is all about inertia and centripetal force.
Inertia looks at two important things that affect all objects;
- An object at rest will stay at rest forever until something pushes or pulls it.
- An object will continue to move in a straight line forever until another force pushes or pulls it.
In this case, swirling the glass rapidly caused the ball to be pushed against the sides of the glass (inertia). Because the glass is curved and swirling in a circle, the ball also was affected by centripetal force which pulls the ball around in a circular motion. As long as the inertia of the ball pushing the ball against the glass was greater than the force of gravity, the ball could remain inside the glass even if it was tipped upside-down. An amusement park gravitron ride uses the same forces, wherein this case you’re being pushed against the sides of the ride as the gravitron spins around.
Variables to test
- Try different weights of balls inside the glass.
- Try different shaped glasses. Can you do this activity with a straight-sided glass?
- What if you vary the inside surface of the glass by adding tape?
Forces, Friction & Movement
Years K to 6
Maximum 30 students
School workshop
60 or 90 minutes
Online Class Available
STEM Full Day Accelerator - Primary
Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials.
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