Amazing Kids! Magazine

Taking Flight with Newton’s Laws

By Enzo Monfre, Sci-Tech Kids! Columnist


Who knows how long man has looked at soaring birds and felt jealous. Leonardo DaVinci was obsessed with designing flying machines in the 1400‘s even though none of his designs ever got off the ground. It took another 500 years to invent the hang glider.

Even the genius of Leonardo couldn’t understand the physics of flight. Then someone named Sir George Cayley, a British engineer figured out that flight required some outside forces including lift, propulsion and control.

However, Isaac Newton was the scientist who’s Laws of Motion really allowed man to fly like a bird. These laws describe the forces that make flight possible.

I had a chance to explore Newton’s laws by flying a real airplane. After a couple days of ground school, we took off in a Cessna 172 SkyHawk. I took off and landed several times and made some amazing turns in the air. We even created weightlessness by doing something called a parabolic arc! I almost lost my lunch!

Here’s what I learned.

Newton’s first law says, “Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.” Ok, what the heck does that mean? It means that if an airplane is not moving it’s going to just sit there until some outside force acts on it. Or if the airplane is moving, it’s going to keep moving until an outside force acts on it.

If the airplane is moving, the outside force is provided by the propeller and the motor. The kinetic force of moving air blasting back from the propeller makes the airplane go forward. It’s the same thing with the airplane in flight. If I’m flying straight, in order to turn, I have to move the controls so airflow is changed – providing a force to turn the airplane.

But you also need Newton’s third law to make it work. The third law of motion says: “For every action there is an equal and opposite reaction.” That means that the blast of air (the force) moving back from the propeller makes the airplane go forward (the action).

The same thing happens to create lift. Lift is what overcomes gravity to keep the airplane in the sky. Air rushes over the wing, which directs the airflow (the force) downward. This downward force makes the airplane go in the opposite direction – up!

It’s the same thing with making the airplane turn – by adjusting control surfaces (like the rudder), it changes how the air pushes on the plane. The air goes one way – the airplane the other.

There are many forces that work on an airplane including drag, gravity, velocity and more. There are also other scientific rules that help (like Bernoulli’s Laws).

What is interesting to me is that scientists still can’t agree as to why exactly airplanes fly.  Even though there are about 45 million flights per year, we still can’t figure out exactly how it works!

But when it does work, we humans give those birds a run for their money. As Leonardo DaVinci said, “For once you have tasted flight, you will walk the Earth with your eyes turned skywards.” I totally get that. I can’t wait to fly again.

One comment

  1. Bill /

    Aviation ROCKS!!!!!!!!!!!!! Oh and cool site.