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Paper Bridge
Paper Bridge
Materials:
Two cups of the same height
Piece of paper
Pennies/coins
Tape
Steps:
Set up two cups about 10 inches from each other
Lay and tape the piece of paper on the inner edge of the two cups so that the paper is barely touching the cups’ surface
Place pennies onto the paper in a row (not stacked) and count how many pennies you can place until the paper falls or touches the table.
Fold the paper in half lengthwise and tape it to the cups. Repeat step 3.
Create a ‘channel’ by folding the paper in half lengthwise (hot dog style) and folding up the edges of the paper to form two walls. Tape the channel to the cups and repeat step 3 again.
See which design held the most pennies. Try folding your paper into different ways to carry even more pennies!
Explanation:
Why are we trying different designs?
The different designs are the independent variable (the thing that we are changing in the experiment). The number of pennies that the bridge can hold is the dependent variable (the thing that we’re measuring). Scientists use independent variables to see how different versions of something, like how the paper is folded, affect the dependent variable. In this experiment, you saw which version of the folded paper was the best at holding pennies!
Why do some designs work better?
Even though each bridge was made with the same material (a sheet of paper), some designs worked better than others! The flat piece of paper probably didn't hold much weight while the folded paper could hold more. The channel design held the most because you changed the shape of the bridge to add another dimension (the vertical walls). A flat/folded piece of paper is easy to bend in the vertical (up-down) direction while the vertical walls are much harder to bend in the vertical direction. This makes the bridge stronger vertically and more able to hold pennies/more weight. Engineers use concepts like this to build the bridges you drive across!
Table: Click on the table and make a copy, or write the table on your own paper!
Share your results with us using this link: https://forms.gle/RqwfUZX7eosEMtWS9
Homemade Catapult
Homemade Catapult
Materials:
7 popsicle sticks
5 rubber bands (preferably sturdier ones)
Plastic spoon
Cotton balls, paper balls, marshmallows, pom-poms, or other small lightweight objects
Steps:
Line up five popsicle sticks on top of each other in a stack
Wrap a rubber band around each end of the popsicle stick stack
Line up the two other popsicle sticks and rubber band them together at one end
Slide the bottom popsicle (in the stack of 2) through the middle of the big stack of popsicle sticks. Make sure that one popsicle stick (in the stack of 2) is above the big stack.
Use two rubber bands to hold the two stacks together at the middle where they cross. The rubber bands should make an X shape.
Line up a plastic spoon with the popsicle stick above the big stack. Slide the plastic spoon through the middle rubber band on this popsicle stick to secure it in place
If you have difficulty doing this, use another rubber band to attach the spoon to the popsicle sticks by tying the spoon to the center like in step 5.
Place a cotton ball or other lightweight object in the spoon
Pull down the spoon slightly and release to see the catapult in action!
Explanation:
How does a catapult work?
Catapults are based on the physics concept of stored energy being released to move an object. Stored energy is typically called potential energy, and the energy of a moving object is called kinetic energy. For your popsicle catapult, when you pull down the spoon, potential energy is stored in the popsicles, rubber bands, and other parts of the catapult. When you release the spoon, the potential (or stored) energy from the catapult is changed, or converted, into kinetic energy of the cotton ball or other object. This means that the object is able to move!
Balloon Car
Balloon Car
*This experiment requires adult supervision. Do not do this experiment without the help of an adult.
Materials:
Plastic bottle
3 bendy straws
2 wooden skewers
4 bottle caps (OR 4 small circle cardboard cutouts)
Balloon
Small rubber band
Tape
Scissors
Small knife (USED BY AN ADULT ONLY)
Steps:
Cut two straws to be the width of the bottle. Do not include the bendy part when cutting them.
Attach the two straws to the bottle using heavy-duty tape. Make sure the straws are parallel and spaced apart.
Cut two wooden skewers to be slightly longer than the straws. Ask an adult to do this step.
Push the two skewers through the two straws
Use a small knife to make a hole in each of the four bottle caps (Ask an adult to do this step) OR use scissors to cut out four small cardboard circles and make a small hole in the middle using the skewers.
Push a bottle cap or cardboard circle through the end of the skewers. Make sure that the bottle caps or circles are able to spin freely
Take the third straw and put the balloon onto the bendy short part of the straw.
Use a small rubber band to tie the end of the balloon onto the straw. Make sure that the rubber band is very secure so that no air can escape the balloon.
Cut a small hole in the top of the bottle (The straws should be at the bottom of the bottle). Ask an adult to do this step.
Push the open end of the straw through the hole to the mouth of the bottle. The balloon should be on top of the car.
Tape the straw to the bottle so that the open end is facing backward, not down.
Blow into the straw to inflate the balloon and hold the open end of the straw closed. Place the car on the floor and release your finger to see the car move!
Explanation:
What lets the car move?
This experiment shows the physics concept of Newton's third law of motion, which states "for every action, there is an equal and opposite reaction." This can be seen by the air coming out of the balloon in one direction causing the balloon car to move in the other direction. Also, energy, specifically potential energy, is stored in the balloon's stretched rubber and the air when you blow into the balloon. This potential, or stored, energy is changed or converted into kinetic energy, or "moving energy," which allows the car to move.
What engineering concepts are involved?
Your balloon car uses a simple machine called a wheel-and-axle that professional engineers use as the basis for their designs and creations. The wheel-and-axle is shown through your balloon car's wheels which have wheels (the bottle caps) and an axle that passes through the wheels (the skewers). This machine allows the two parts to rotate together and reduces the amount of friction and resistance to the object moving.
Dancing Foil
Dancing Foil
Materials:
One sheet of aluminum foil
Bowl
Water
Measuring cup
Directions:
Crumble the sheet of aluminum foil into a sphere
Pour 5 cups of water into the bowl
Place the aluminum foil ball into the bowl
What happens? Why?
Explanation:
When the aluminum foil is placed in the water, it is experiencing an upward force from the water that helps it keep afloat. This ability for the foil to float in the water is called buoyancy!
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