Water Colors (page 3) — You should usually water the ground around your plants, not just the leaves. While some water is absorbed through leaves, the plant will get its water more easily by the process you saw in the experiment — through its roots in the ground.
Falling Leaves (page 5) — The leaves change color when the days begin to get shorter. With less light, the trees are not able to produce as much chlorophyll, and this begins the process of falling leaves.
Blue Blockers (page 16) — The sunglasses do in fact block nearly all of the blue light that hits them. As a result, you shouldn't see much of the color blue when you look around. What you will see, however, is a lot of color that isn't blue. The term for this is complement, and the complement of blue is yellow. Do you see yellow? Actually, yellow light is made up of two other colors: red and green. So you should notice rich greens and reds as well.
Walking on Eggshells (page 19) — Both the bed-of-nails trick and snowshoes use the same principle as the egg experiment. While a single nail would pierce a person's skin, using hundreds of nails spreads the weight of the person's body evenly over the whole bed and no single nail has to hold more weight than it can handle. The performer isn't hurt. NOTE: Magicians are professionals who practice under very safe conditions. Never try a “trick” like that at your own home!
If you tried to walk in very deep snow in your regular shoes, you would probably fall right through. A snowshoe spreads your weight evenly over its whole shape (kind of like a tennis racket). By distributing your weight, no part of the snow has to hold more weight than it can, and you stay on top of the snow. See if you can find more examples of this weight-spreading phenomenon in nature!
Boiling Ice (page 25) — When the ice melts into liquid water, it is still very cold. In fact, it's 0ºC (32ºF), just like the ice was. Water can boil only when it is all at 100ºC (212ºF), so before it can start boiling again, all the melted ice must be warmed up to 100ºC. Once all the water in the pot is at that temperature, it will begin boiling once more.
Cleaning Pennies (page 41) — The other coins listed are not coated with copper. The cleaning reaction works only with a weak acid (like the vinegar/salt solution) and copper. You won't get the same results with the other coins.
Seesaw (page 49) — Two pennies 6 inches away will balance, as would one penny located 12 inches away. Unfortunately, on this ruler, the farthest you can get away from the fulcrum is 6 inches. Another combination that would work would be eight pennies located 1½ inches from the fulcrum (because 8 × 1½ = 12).
Teeter-Totter (page 49) — The heavier person needs to sit closer to the middle (the fulcrum) so his or her weight doesn't count as much. With your parents, the weight difference might be big, especially if you are young. Your parent might have to sit almost at the middle to make the teeter-totter balance, but it can be done.
Cushioning the Blow (page 51) — Some examples: boxers wear padded gloves; bicycles have padded seats; tennis shoes have padded soles; air bags in cars soften the impact in an accident; and catchers in baseball use a soft, oversized mitt to catch pitches.
Corners (page 55) — Helium is lighter than air, so unlike most objects, it doesn't fall to the ground. Instead, it rises upward, toward the sky. When the car turns, everything in the car wants to keep moving in a straight line except the balloon. It wants to follow the turn. For more fun, watch what a balloon does when you speed up and slow down in a car. You'll soon see why balloons in a car can be a safety hazard.
Magnetic Electricity (page 61) — The electromagnet formed by the electricity works only when the battery is attached. When you disconnect it, the compass returns to normal. However, when you place the wire under the compass, the magnet formed by the electricity is flipped so it points in the opposite direction. Thus, the compass also points in the opposite direction.
Electromagnet (page 63) — One of the most common places you'll find electromagnets of this kind is a wrecking yard. There they use a crane with an electromagnet turned on to lift large vehicles into the air, and when they are ready to drop them into their new location, they simply turn the magnet off and the vehicle drops.
Wind Speed (page 77) — First, you need to measure the radius of your anemometer (the distance from one of the cups to the center of your device) in inches. Then you multiply that number by 6.28 to find the circumference, or the distance a cup will travel in one complete circle. Now, count the number of circles, or revolutions, the marked cup makes in one minute. Multiply this number times your circumference and you'll have a speed in inches per minute. To convert this speed to miles per hour, simply divide this final result by 1,056 and you'll have your speed in miles per hour.
Your radius is approximately 8 inches. This makes a circumference of 8 × 6.28 = 50.24 inches. If you count 40 revolutions in one minute, then the cup travels a total of 40 × 50.24 inches = 2,010 inches in one minute. Divide this result by 1,056 and you get a speed of 1.9 miles per hour.
Land Warmer (page 79) — Only the top layer of sand gets warm on a typical beach. The sun cannot reach the lower levels of sand, so it isn't able to heat those levels. For the same reason, the top layer of water in a pool or even a small lake is often warmer than deeper water.
Icicles (page 83) — Epsom salts is often used to help heal bruises and sprains. It is also used in the production of high fructose corn syrup, something you'll find in most soft drinks. One of its most popular uses is in bathtubs for people who want to soak and relax. If you have problems with raccoons, you can sprinkle it around your garbage cans and it will drive the raccoons off without harming them. As an added benefit, it is great food for your plants, too!
Space of Air (page 85) — In the summer, balls can become very bouncy when left in the sun, but in the winter they become a little flat if left in the cold. Also, if you keep juice in your refrigerator in a pitcher with a cap or tight lid, take it out and let it sit on the counter for a few minutes with the lid still closed. When you finally open the lid, you'll hear the air escape. For another fun experiment, blow up a small balloon and place it in the freezer. You'll be able to see the effects of air compressing as it cools.
Constellations (page 90) — Look toward the north for what appears to be a large cup with a handle. This is called the Big Dipper, but it is actually part of a larger constellation called Ursa Major — the Great Bear. Look on a star chart to see the shape of the bear. Using the two stars at the far right of the dipper, trace a straight line upward until you encounter another star. It isn't the brightest star in the sky, but it's an important one. It's the North Star (Polaris) and it indicates the direction of due north.
The North Star is actually part of a constellation called the Little Dipper, or Ursa Minor. Some people say that the Little Dipper pours its contents into the Big Dipper.
Other interesting constellations to find include Orion, the hunter (recognizable by his “belt,” which is made up of three stars in a row), which is visible throughout the winter months; Cassiopeia, the queen (a W-shaped collection of five stars found in the northern skies); Gemini, the twins (winter); Pegasus, the winged horse (autumn); and Leo, the lion (spring). See how many you can find on your own!
Taste Buds (page 103) — As you saw earlier, your sense of smell has a major impact on your ability to taste. When your nose is plugged, your taste buds aren't able to send the proper signals to your brain to tell it what kind of flavor they are tasting.
Cyan, Black, and Yellow (page 105) — The complement of red is cyan, for green it's magenta, and for blue it's yellow. The complement of white (all colors) is black (no colors). That is why a flag of yellow, black, and cyan should produce an afterimage of a flag that is red, white, and blue.
Reaction Time (page 111) —
If the ruler fell…
your reaction is…
Balance (page 115) — Just having the wall close by serves as a reminder that something is fixed and not moving. You should find it easier to stay standing, especially on one leg, when you lightly touch the wall.
Center of Gravity (page 117) — Take a yardstick and place your two forefingers under it to support it. It doesn't matter where you put them. Now, slowly move your fingers toward one another, keeping the yardstick balanced. They will meet at the location of the yardstick's center of gravity (usually the middle). You can hang something on one end to change the center of gravity and try it again — you will always find it using this method.