Use a measuring tape or a meter stick to measure the distance if you’re in a field. Mark the starting and ending points with a piece of string or a cone.
You can also use a watch to time the runner, but it will be less accurate.
Multiplying 10 m/sec by 3,600 (the number of seconds in an hour), the runner traveled 36,000 meters per hour, or 36 kilometers per hour (1 kilometer equals 1,000 m). Multiplying 32. 8 feet per second by 3,600, the runner traveled 118,080 feet per hour, or 22. 4 miles per hour (5,280 feet equals 1 mile).
Measure the distance with a tape measure. Try to be as accurate as possible with your measurements.
If you are perfectly in sync, you shouldn’t hear the echo, just your clap.
Clapping 11 times also gives your friend enough time to start and stop the watch accurately. Perform this step multiple times and average the times together to get a more accurate measurement. To average the trials, add up all the times and divide by the number of trials.
For example, let’s say it took 2. 89 seconds for the 11 claps. To find speed we take the distance, 1000 meters, and divide by the time, 2. 89 seconds to get a speed of sound of 346 m/sec. The speed of sound at sea level is 340. 29 m/sec (1,116 feet per second or 761. 2 mph). [5] X Research source Your calculations should come close to this figure, but may not match it exactly, especially if you aren’t at sea level. At higher altitudes, the air gets thinner and the speed of sound is slower. Sound travels faster through liquids and solids than it does through air because sounds moves more quickly through materials of higher density. [6] X Research source
You can either buy an anemometer or make your own. To make your own, get five three-ounce paper cups, two straws, a sharpened pencil with an eraser, a stapler, a small sharp pin, and a ruler. [8] X Research source Color the sides of one of the cups to make it distinct from the others. Punch a hole in the side of four of the cups about 1 inch from the rim. In the fifth cup, punch four holes equally spaced around the cup about 1 inch from the rim. Also, punch one hole in the bottom of this cup. Push one straw through the side of one of the cups leaving about 1 inch of straw inside the cup. Staple the straw to the side of the cup. Feed the rest of the straw through the fifth cup with 4 holes in one side and out the other. Place a second cup on the end of this straw and staple it in place. Make sure all of the cups face the same direction. Repeat the above step with the other two cups, feeding the straw through the remaining two holes in the middle cup. Again, make sure all cups are facing the same direction. Carefully, place a pin through the intersection point of the straws in the middle cup. Feed the pencil through the bottom hole of the fifth cup and push the pin through the eraser. Make sure your anemometer can spin freely. If so, it is now ready to use. If not, adjust the pencil so the eraser is not directly up against the straws.
Measure the distance from the center of the anemometer to the center of one of the cups. This is the radius of the anemometer. Doubling this distance is the diameter. The circumference of a circle is equal to the diameter times the constant pi or 2 times the radius times pi. For example, if the distance between the center of the cup and the center of the anemometer is 30 cm (1 foot), the distance the cup travels in a single rotation is 2 x 30 x 3. 14 (rounding pi to 2 decimal places), or 188. 4 cm (74. 2 inches).
If you don’t have a timer, have a friend watch the clock, while you count the rotations. If you purchased an anemometer, mark one of the cups in some way to allow you count properly.
For example, your anemometer has a radius of 30 cm (. 98 ft), therefore it travels 188. 4 cm (6. 18 ft) in a single rotation. If it rotated 50 times during your count, then the total distance is 50 x 188. 4 = 9420 cm.
For example, if you counted the number of rotations in 10 seconds you would divide the distance traveled by 10 seconds. Speed = (9420 cm/10 sec) = 942 cm/sec (30. 9 ft/sec). Multiplying 942 cm/sec by 3600 gives 3,391,200 cm/hr, divided by 100,000 (the number of centimeters in a kilometer) or 33. 9 km/hr. Multiplying 30. 9 feet per second by 3,600 gives 111,240 feet per hour, divided by 5,280 gives 21. 1 miles per hour.
