Newton’s 1st Law

WHERE’S the REMOTE?  (Newton’s 1st Law)

Students know the first law, but rather than regurgitate the phrasing learned in texts, we will focus on meaningful examples to translate that language to them. 

 

“Objects at rest tend to stay at rest”
1.  Stacked Blocks
Stacked Blocks

In this demonstration, we will focus on moving a block out from underneath another block without disturbing the top block.  A simple hit with hammer will send the bottom block moving, and students will see the top block simply drop down in place.
2.  Where Did the Floor Go?
What will happen to the skater if the floor is pulled out from under them?

In this demonstration, a cart will be pulled out from underneath a stationary skater, and students will see that the skater remains in place, simply dropping to the floor.

Objects at rest…stay at rest!

“Objects in motion tend to stay in motion”
3.  Air Track
Using an air track to create a nearly frictionless environment, a cart will glide along the track.  Students will be able to see that the motion of the cart is unchanged.

“Unless acted upon by an outside force”
4.  WE’re Not Smarter than the romans (Air Track with Friction)
Now, the air track will be turned down and eventually off, providing friction to the environment.  When the cart is send along now, it will be difficult to make it glide.  What is the difference?  There is an outside force altering its motion.

The important concept for students to go into Newton’s laws with is that acceleration is a change in motion.  The important concept for them to leave Newton’s 1st Law with is that  UNLESS there is an outside or unbalanced force present, there will be no acceleration.

In other words: nothing changes unless you force it to change.

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