The First Law of Motion: The Tower of Coins
Initial Publication Date: August 25, 2009
Summary
In this physics activity the students will attempt to push or pull out the bottom nickel, from a stack of 12 nickels, without knocking over the stack. They will have a variety of tools to use to try to move the bottom nickel.
CollapseLearning Goals
This activity will provide the students with opportunity to try the pushing or pulling of a nickel on the bottom of the stack of nickles using several tools. They will soon discover that the faster they push or pull the bottom nickel the more success they will have. They will be observing and thinking of other possible methods of moving the nickel. The students will practice inquiry.
Context for Use
This is a classroom activity. This is a good introduction to the concept of inertia, "laziness of an object".The students should be able to work on a sturdy table.
Description and Teaching Materials
Materials needed: 12 nickels, 12 pennies, 12 washers, 12 checkers, 12 round crackers, a flat metal spatula, a rubber spatula, a fork, a butter knife, and a table. Have the students tower 12 nickels on the table. They should try to get the bottom nickel out of the stack by pushing or pulling it without making the tower tip over. Have the students select a spatula, knife or fork to help them. After they are successful, encourage them to try the other round items to make towers. What happens if you stack the crackers, washers, or pennies? Or what if you used more than 12 nickels? Try using other objects from the classroom to remove the bottom object. These things could be a ruler or a card. Use predicting when changing one thing- one variable.
Teaching Notes and Tips
The tower of nickels is at rest or not moving. Objects at rest don't move unless you push or pull them. So, to make the bottom coin move, you need to push or pull it. To make it move without tipping the tower, you'll need to push or pull quickly. Why? Because of frition. Friction is a sticky force that appears when 2 objects rub against each other. If you push or pull slowly friction helps pull or push the tower along with the bottom coin. If you push or pull quickly, the coins still rub, but the friction force doesn't have time to get the stack moving. So the coin shoots out without pulling the tower with it.
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Assessment
The assessment will be oral and a drawing for the youngest students. The older students can write an observation. The goal is for all of the students to be able to move the coin on the bottom of the tower of coins.
Standards
0.1.1.2.1. The Practice of Science