How much force can a rubber band withstand before breaking? Do rubber bands that stretch longer take more or less force to break? How does the elasticity of a rubber band change with temperature? Use a spring scale to measure the applied force, and a meter stick or ruler to measure the change in length. Recording with a video camera (or possibly two) can help you to capture the values at the moment before the rubber band breaks. You can change the temperature of the rubber bands using…
Hooke's law says that the opposing force of a spring is directly proportional to the amount by which the spring is stretched. How accurately Hooke's law describe the behavior of real springs? Can springs be used to make accurate scales for weighing objects? Spring into action and find out for yourself with this project.
Are you interested in things like prosthetic limbs and artificial joints that can help people with disease or injury to lead a normal life? Or maybe you're interested in sports medicine or physical therapy? Either way, this project could be a good match for you. Find out how the tension on the knee joint changes as a function of angle by building a simple mechanical model.
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- Less Details
Long (2-4 weeks)
To do this project, you should be handy with basic woodworking tools
Specialty item (guitar string tuning mechanism)
Average ($50 - $100)
Adult supervision required (power tools used for assembly)
Do you ever go camping with your family and roast hot dogs and marshmallows over a campfire? If you want your campfire to burn long into the evening, what is the best wood to use? Do research on the necessary conditions/materials to sustain a fire and on the properties of different types of wood. Which properties do you think will be most important for determining how fast the wood burns? For example, how do you think density would be related to burning rate? Why? Measure the density and…
How does ski wax affect the sliding friction of skis? You can model this with an ice cube sliding down a plank: how high do you need to lift the end of the plank before the ice cube starts to slide? Try this with one side plain wood and the flip side waxed wood (use paraffin wax, candle wax or ski wax). Make sure both sides are equally smooth to start with. Do at least three trials. More advanced: using what you know about the forces acting on the ice cube, derive equations to calculate the…
How strongly do different types of nails hold in wood? Try different diameters of nails, and try pounding them to different depths. To gauge the holding strength, measure how difficult it is to remove the nail. Can you pull it out with a pair of pliers? Can you remove it with the hammer claw? Do you have to push only a little bit, moderately hard, or as hard as you can? Do you need a crowbar? What happens if you pre-drill holes for the nails, using drill bits that are different…
You can make a very simple hovercraft with a stiff, disposable plate-a pie plate should work well-and a balloon. Glue a square of cardboard in the center of the bottom of the plate. Make a small hole through the center of both of these layers. Enlarge the hole slightly with a pencil. Push a balloon through the hole so that the opening is on the front side of the plate, and rest of the balloon sticks out from the back. Blow up the balloon, then set the plate down (balloon side up). What…
Try different wind turbine/propeller (chord length, pitch) designs by making models from balsa wood. Connect the spinning axle to a DC motor and measure the voltage produced across a resistor to measure power output. Use fan as wind source. (Judge, 2004)
You can model this with an ice cube sliding down a plank: how high do you need to lift the end of the plank before the ice cube starts to slide? Try this with one side plain wood and the flip side waxed wood (use paraffin wax, candle wax or ski wax). Make sure both sides are equally smooth to start with. Do at least three trials. More advanced: using what you know about the forces acting on the ice cube, derive equations to calculate the coefficient of friction for each case. Variation:…
Fill a jar a little more than half full with fresh water. Make a solution of salt water, and add a drop or two of food coloring to it. Pour the salt water solution into a plastic cup with a small hole in the bottom, and then place the cup in the jar with fresh water. (The only connection between the fresh and salt water should be via the hole in the bottom of the cup.) With the right combination of hole size and salt concentration, you will see an oscillating current develop in the jar. …
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