Tag Archives: adding and subtracting forces

Physics 2 Putting Forces Together

Do you like to fly paper airplanes? The beginner model doesn’t fly very well. A modified one zips along.

What do paper airplanes have to do with physics and forces? They can show us how putting forces together changes the strength of the forces.

Tyler Green

Introducing my helper for this physics project Tyler Green.

Question: How does putting forces together change them?


Paper airplane



Large room


Make your favorite paper airplane

Set up the fan at one end of the large room

Stand by the fan, not turned on, and fly your paper airplane

throwing a paper airplane

Paper airplanes have several forces working on them. Air pushes them up and back. Your hand pushes them forward. Gravity pulls them down. Tyler isn’t thinking about this as he practices flying his airplane.

Put a piece of tape where it lands

Repeat this two more times

Turn on the fan

Fly your paper airplane several times over the fan so the moving air catches it

Mark where the airplane lands each time

Walk out from the fan to about where your paper airplane would land with the fan off

Fly your paper airplane toward the fan and into the stream of air several times

Mark where it lands each time


Describe where the paper airplane lands

Without the fan

With the fan

Against the fan

Describe how the paper airplane flies

Without the fan

With the fan

Against the fan


What forces are acting on your paper airplane when it flies without the fan?

Does the air from the fan provide a force?

putting forces together can mean increasing the forces working on an object

Who says physics is boring? Not Tyler. His paper airplane really took off when the fan’s air current helped push it aloft and across the room.

What happens when this force is added to your paper airplane?

What happens when this force acts against your paper airplane?

How does putting forces together change the force acting on an object?


What I Found Out:

It is hard to fly a paper airplane and take pictures of it flying at the same time. I asked Tyler Reed for help. He was a bit young for the physics but very enthusiastic about flying the airplanes.

A paper airplane launched into the air has several forces acting on it. One is the push you give it to make it go called thrust. Another is gravity pulling it down to the ground. Another is the air which helps hold it up but pushes against it slowing it down.

Tyler had a lot of thrust so the paper airplanes, two styles, flew very well without the fan. They zipped along moving up a little then going lower until they hit the floor at the laundromat where I do the physics projects as there is so much more room than at home.

With the fan turned on the paper airplanes flew higher and farther before. This depended on Tyler throwing the planes near the fan so the fan’s air could push on them.

adding forces together can slow objects down

Tyler threw the paper airplane at the fan. If you look carefully you can see the airplane off to the right side and slightly below the fan pushed there by the air current.

Then Tyler threw the paper airplanes at the fan. The air was still being pushed out from the fan. Now the air stream was pushing against the airplanes. They tended to go up over the air current, turn aside out of the current or dive bomb into the floor.

Putting forces together changes how an object moves. When the forces act in the same direction, they add up to a bigger force so the object moves farther. When the forces act against each other, they make the object go slowly, stop or turn aside from the force.