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Inertia - Coin in Cup (Rena Benor)


Rena Benor
Principles Illustrated : Inertia

  1. Object at rest stays at rest
  2. Object at rest stays at rest unless acted upon by an outside force.


                    PHYSICS1.b  Grade Nine through Twelfth:

  • Students know that when forces are balanced, no acceleration occurs; thus an object continues to move at a constant speed or stays at rest (Newton’s first law).

Questioning Script

Prior knowledge & experience:

Tower of blocks will topple when one is pulled out from below.

Root question:

What will happen to the penny when the card is pulled away?

Target response:

The penny stayed in place and then fell into the cup, because it acted in accordance with the First Law of Inertia; “An object at rest will remain at rest until acted upon by an outside force”.

Common Misconceptions:

Most students will predict that the coin will slide off with the card and go flying.

Coin and tumbler
a Place the coin on the card, and place the card over the open end of a beaker.
b Flick the card away sharply and observe the effect of the coin's motion.


Nuffield Foundation  IOP Institute of Physics

YouTube :

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