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Science Sunday: Newton's Third Law

Posted at 9:58 AM, Jan 29, 2023
and last updated 2023-01-29 12:58:32-05

BAKERSFIELD, Calif (KERO) — In 2022 180 rockets were successfully launched from the earth into space, with many of those launches happening in California.

We are breaking down how something as complex as a rocket, relies on one the most basic principles in physics.

Newton’s third law says that forces act in pairs. Which means if you push on something, it pushes it back on you. That’s why if you are sitting down and push on your desk, you will move. It might not seem like rocket science, but it is.

At nearby Vandenberg space force base, Newtons third law is used to propel rockets that weigh thousands of pounds away from the earth at thousands of miles per hour. These rockets cost millions of dollars, but one can make our own for quite a bit cheaper than that.

What you need:

  • Balloon
  • Styrofoam cup (stabilizer)

What you've got here is a balloon rocket that uses a styrofoam cup as a stabilizer. First cut the cup down to just about an inch in height, poke a hole in the top and feed the balloon through the hole.

Once you let go of the balloon, the air inside the balloon will rush out, and the rocket will fly.

How does this relate to newtons third law? When we let go of the balloon the pressure inside creates force that pushes the air down through the straw. But newton’s third law says that forces act in pairs. That means the pressure inside the balloon is also pushing up on the balloon. That upward force is what makes the rocket fly.

The upward force is called thrust and it’s the force that propels every rocket. From the ones that weigh thousands of pounds, to the ones that fit in your hand.