Seventh Grade Science Experiments (Page 184)

Materials for Sound Barriers

Science Fair Project Idea

Scientific Method

What are the best materials to use for blocking out unwanted noise from the environment? You can build a test box (or test frame) around an audio speaker. Use a sound level meter to measure the speaker output. Use different materials to cover the walls of your test box (or frame), and see which materials do the best job at blocking the sound. For a more advanced project, perform your tests using different sound frequencies. Are some materials better at blocking certain frequencies than… Read more

Mean & Green: Fruit & Vegetable Hardening

Science Fair Project Idea

Scientific Method

When you open a can of green beans, have you ever wondered why the beans are not mushy, or more like a puree? Canning requires boiling the beans for a long period of time to kill bacteria, so why don't the beans fall apart into small pieces? Some fruits and vegetables—like cherries, apples, potatoes, sweet potatoes, beets, carrots, beans, cauliflower, and tomatoes—have the ability to undergo hardening, or firming of their plant tissues. A special enzyme, called pectin methyl… Read more

Measuring Concussion Risk in Football and Other Contact Sports

Science Fair Project Idea

Scientific Method

Playing sports can be a lot of fun, but some sports pose higher risks of concussions, or brain injuries resulting from collisions, especially in contact sports like football. Some coaches, teams, and players use new warning devices mounted on helmets that sound an alarm after the head receives a serious impact. This gives an advanced warning of concussion risk (possibly before any of the medical symptoms might appear), signaling that the player should stop playing and see a medical… Read more

Measuring Height Or Distances with a Camera

Science Fair Project Idea

Scientific Method

If you know or calculate the field of view for your camera, you can use it to measure distances and the height of almost anything. It's all a matter of basic trigonometry. Read more

Measuring Speed with a Video Camera

Science Fair Project Idea

Scientific Method

A video camera records 30 "frames" or distinct images per second. (That's for an NTSC camera in the U.S. PAL cameras in other areas of the world take 25 frames per second.) You can use this fact to time events and measure speed. One student has used a video camera to measure the speed of an arrow shot from a bow. The following project can help you set up your experiment: Distance and Speed of Rolling Objects Measured from Video Recordings. Read more

Measuring Surface Tension with a Penny: Weekly Science Spotlight

Blog Post

What makes drops of water on a penny appear to pool together on the top of the penny as a large drop rather than run over the sides? Attraction of the water molecules holds the surface of the water together until the amount of water is too great and spills over the edge. This attraction results in surface tension—something we can see visually in the way the droplet may seem to hold together as a jiggly whole rather than flowing freely over the edges of a surface. You can see surface… Read more

Measuring the Diameter of the Earth's Core with Seismic Waves Around the Globe

Science Fair Project Idea

Scientific Method

When an earthquake occurs, seismic shock waves travel out through the earth from the source of the event. The shock waves travel through the earth or along the Earth's surface, and can be recorded at remote monitoring stations. Some of the waves that travel through the earth are blocked or refracted by the Earth's liquid core, which means that monitoring stations located certain distances from the earthquake do not detect these waves. This creates a "seismic shadow" that you can use to… Read more

Measuring Up

Science Fair Project Idea

Scientific Method

Measurements are very important for scientists. It is especially important that the measurements be accurate. Think about how important accuracy is when you want to know if you are taller than a friend of yours, every inch counts! In this experiment, you will investigate how different objects can be measured with accuracy. Are small or large objects more difficult to measure? Who in your family is the best at measuring? Maybe it will be you! Read more

Measuring Vibrational Frequency with Light

Science Fair Project Idea

Scientific Method

Strike a key on the piano, and you hear the string vibrating. Just about any object vibrates when it's knocked, but how much and how fast? What properties of the material affect the way it vibrates? This project helps you find out. You'll build a simple light-sensing circuit for measuring the frequency of vibrating springs. Read more

Mechanical Science Scissor Lift

Blog Post

Kids can experiment with physics and mechanical engineering at home or in the classroom by making a fun cardboard scissor lift. Explore Mechanical Science Simple devices and machines can be used to help solve everyday problems. A scissor lift is a device that can fold up compactly but can extend to a great length. This kind of device uses a system of mechanical linkages and can stretch out or contract with an accordion-like motion. In the Build a… Read more

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