Newton’s first law of motion states that objects have the tendency to retain its motion or the lack of.
If a body is at rest, it has the tendency to remain at rest; If a body is moving, it tends to keep moving in a straight line at a constant speed.
This is also called the law of inertia.
Inertia is an object’s tendency to stay at rest, or keep moving until an external force is applied to change it.
Let’s do an inertia experiment.
We are using plastic eggs, but you can use real eggs to do this, too.
It was so much fun that my kid wanted to do it again and again.
- egg, I used a plastic easter egg, but you can certainly use a real one 🙂
- empty toilet paper roll
- an unbreakable pan with a raised edge or a shallow plastic container
- a glass big enough for the egg
- tray (optional: to catch the broken egg if you use real eggs and don't succeed on first try)
- adult supervision
- Place the glass on a sturdy table.
- (Optional) If a real egg is used, fill the glass with water. Otherwise, an empty glass is fine.
- Center the pan on top of the glass.
- Put the toilet paper roll vertically in the middle of the pan directly over the glass.
- Carefully place the egg on the top of the paper roll.
- In one quick move, knock the pan sideway off the glass.
- Observe the egg fall directly into the glass.
Why does the egg fall right into the glass while the paper roll and the pan flies sideways?
This can be explained by Sir Isaac Newton’s First Law of Motion, which states that an object at rest remains at rest and an object in motion stays in motion with the same velocity (speed and direction) unless acted upon by an unbalanced force.
Because the egg is not moving at the beginning, it wants to stay that way.
When the pan is knocked off by you hand, its raised edge in turn knocks off the paper roll.
When the support of the egg is removed, gravity applies a net downward force that pulls the egg straight down.
The egg then drops right into the glass.
Try the experiment again using
- paper rolls of different lengths.
- different types of support for the egg.
- different objects on top of the paper roll.