The Science:

About Our Science Content: This is the first of our science sections for the Wright Again project covering the Wright brothers' development of powered flight. We will repeat the same science concepts throughout our science lessons and show many examples. We may use mathematics from time to time. Don't worry if you cannot follow the math—it may be something you have not learned in school yet, so you may skip it if you want. We will mark these sections as "Optional." We feel it is more important for you to understand the general idea and examples to learn how the Wright brothers achieved powered flight.

Forces: What Is A Force?
Have you ever played the game "tug-of-war" or "arm wrestled" with someone? In tug-of-war, one person (or team) holds one end of a rope. Another person or team of people holds the other end of the rope. Then, at the same time, both groups PULL on their end of the rope. Who wins? The group that can pull the rope with the most force wins. Similarly, in arm wrestling, the person who pushes their opponent's arm down by applying the most force wins.

In our example of "tug-of-war," you can see that the forces (the pushes and pulls) are acting in two directions: right and left. Now, look at the next picture below. The team on the right is pulling to the right and the team on the left is pulling to the left. However, the team on the right is winning. The team on the left is being pulled over the line.

What do you think would happen if the forces acted on our tug-of-war teams in more directions, not just from the left and the right? What direction would the players move if forces also came from above, below, in front, and behind the tug-of-war teams?

Let's examine this situation with another example. You and a friend are walking your St. Bernard dog. Your dog is very large—he weighs more than you do. Your friend is walking next to you. [Note: Orville Wright had a St. Bernard named Scipio. Scipio weighed 16 pounds when Orville brought him home as a puppy. However, Scipio grew and weighed 160 pounds!]

All of a sudden a strong wind begins blowing. At the same time a ball flies by your dog, who decides to chase it. The wind is blowing hard and creating a force against you, pushing you backwards and making it more difficult to walk. Your St. Bernard begins to run, pulling you forward. Oops! Your friend grabs your arm and pulls you sideways. You're being pushed and pulled in several directions. Which way will you go?

Remember our example of the tug-of-war teams. The direction and the speed of the tug-of-war force will be dependent on the strength and direction of all of the forces created by both teams added together. Scientists and engineers refer to this as the "sum of all the forces."

Now what happens? Instead of a St. Bernard you are walking a small dog, like a Chihuahua instead of a St. Bernard. Do you think the direction you will be pulled by the wind, your friend, and your dog will be different? Yes, definitely. Your Chihuahua is not able to pull you forward with the strength and force of the St. Bernard.

Math: Optional
In science, engineering, and mathematics, forces are a special type of quantity called a vector. Vectors have a magnitude (strength or size) and direction. When you add forces you are really adding both the magnitude (strength) of the force and its direction. Which way will a force move? You need to add both the magnitudes and directions of all the forces together.