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How Things Fly Airplane image
What's Going On?
Lesson Plan 1 - Activity 1A - Activity 1B - What's Going On?


You probably noticed that taller kids didn't necessarily have higher jumps.Remember, you measured the jump height from your reach (the standing mark) and not the ground. The best jumpers in the world can clear heights up to 2.4 meters (8 feet), but they lift their center of mass considerably less than that distance.

Did you have a hard time measuring your time in the air? You're not alone. Even the best jumper remains airborne for less than one second. Still, you can compute your airborne time by using the table below. Look down the first column for your jump height and read across to find your time.

Is jumping really flying? Yes and no. Some things like rockets, cannonballs, and baseballs fly like jumping kids: They are pushed into the air by engines or muscles. Airplanes are more complex: Engines push them forward, and air pushes and holds them up. Thrust, drag, weight, and lift are the four forces that work together to make things fly. You already know something about each of them, although you might not have called them by their names. If you thought that having stronger muscles, springy shoes, or a rocket booster might help your jump, then you were thinking about thrust (the force that pushes you during flight). If you thought that a slick suit or helmet would make you jump higher or that a parachute would keep you in the air longer, then you were thinking about drag (the resistance of air against things that fly). If you thought about jumping higher by losing weight, changing clothes, or visiting the Moon, you were thinking about weight (the force that holds you to the ground).

Most people have experienced how thrust, drag, and weight can help them jump higher, or "fly," but few people are familiar with lift. Lift is a push that comes from the air. You were thinking about this force if you decided that wearing wings or holding helium balloons would help you jump higher. While planes and birds have to be moving to get enough of this push to fly, hot-air balloons are light enough for their size that the air will lift them up whether or not the balloon is moving.

Does everything that flies use all four forces? Nope. Only two forces, weight and thrust, act on spacecraft. Lift and drag are not factors in spacecraft flight, because there is no air in space.

This was a quick overview of the forces of flight. Don't stop here, though. Ask your teacher for help in finding more information about how high you can fly. 

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