The Great Chase

Whether you pretend that a mouse is going after a block of cheese or you’re chasing after your siblings, this fun little project will have you skittering with joy!As the mouse chases the cheese down the rubber band, they both bounce back and forth instead of falling straight down. The added drama in the chase happens because of their centers of mass!When gravity pulls down on an object, like a broom or a mouse or some cheese, it pulls on all the parts of that object. But different parts of the object might be heavier or lighter, like how a broom’s handle is heavier than its head. If you tried to balance a broom right in the center, the greater mass on the handle side would tip the broom and make it fall over. But there is a point where the weights on both sides are equal, with part of the broom handle on one side and some of the handle and the head on the other. That balancing point is called the center of mass.

As the mouse (and cheese) falls down the rubber band, its center of mass is somewhere in its middle. The center of mass isn’t being supported, so just like an unbalanced broom, so the mouse will start to turn as it falls. When the mouse turns, the straw hits into the rubber band and stops the fall. But because the rubber band is elastic, it bounces the straw back off the rubber band, letting the mouse continue to fall downward in a bouncy path.

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• Step 1

Gather your materials.

• Step 2

Draw or print an image (or a few!) on a piece of cardstock. This is what will “skitter” down your rubber band. Tip: We used a mouse and a few blocks of cheese, but you can try anything - like a car chase, a bird, or a firefighter!

• Step 3

Cut out the images.

• Step 4

Cut the straw into 1” pieces.

• Step 5

Draw a 1” x 2” rectangle on a piece of paper. Then, cut it out.

• Step 6

Stick a piece of double-sided tape to the rectangular piece of paper.

• Step 7

Stick the straw onto the double-sided tape in the middle of the piece of paper. Then, fold the rectangle in half along the straw.

• Step 8

Use double-sided tape to attach the paper-wrapped straw underneath the left side of your image.

• Tip

Make sure the straw is lying parallel to and sticking out from the image.

• Step 9

Repeat steps 5-8 for as many images as you have.

• Step 10

Decorate your images! Then, cut the rubber band in half and string the images onto it.

• Learn moreMagnifying graphic

Can you figure out a way to make the mouse fall without bouncing on the rubber band? Try moving around where you put the straw, closer and further from the center of the shape. If there’s a single point where the mouse goes down without spinning, that might be the center of mass!

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