In my previous STEM for Kids post I mentioned how much my kids and I love to read. I’ve taken them both to story time at the library regularly since each was child was about 9 months old. We have so much fun singing songs, listening to stories, and doing fun activities with the librarians.

Last week during toddler story time at our local library they gave out straw rocket kits as part of the craft time (I’ve seen similar projects all over Pinterest for years, but this is the first time we’ve tried it). My son and I had so much fun assembling and launching the rockets together after we got home. I took a few slow motion videos of his launches and the videos were so hilarious we couldn’t stop laughing! My baby girl liked playing with the straw and had lots of laughs with us, so I’d say it was a success all around.

We had so much fun I decided to share this simple craft and the science behind it (because this blog is called Engineering Emily after all…).

Let’s start by talking about Newton’s Laws of Motion.

Sir Isaac Newton published three laws of motion in 1687. Newton’s laws of motion are physical laws used in classical mechanics. Most engineers are likely familiar with Newton’s laws of motion. We learned about them in physics classes and applied them in our engineering classes. The laws are summarized as follows:

  1. An object at rest remains at rest and an object in motion remains in uniform motion unless an unbalanced force acts upon it.
  2. Force is equal to mass times acceleration (F=mA)
  3. For every action, there is an equal and opposite reaction.

All three of these laws can be applied to our straw rockets.

Newton’s first law of motion can be demonstrated both at rest and in motion. An example of Newton’s 1st law at rest is when the rocket is sitting on the launcher, it will remain there until a force (your child blowing air into the straw) acts on it. An example of Newton’s 1st law in motion is the rocket will continue to move in the launched direction until a force acts upon it (gravity) and cause it to slow down and fall to the ground.

Newton’s 2nd law is demonstrated by scaling the F=mA equation. For example, using a larger launch force (puff of air by your child) causes greater acceleration of the rocket. A greater rocket mass will result in a slower acceleration (so consider this when you size your rocket, and select paper and decorations!)

Newton’s 3rd law is demonstrated by blowing air into the bendy straw (action), which causes the rocket attached to the big straw to launch (equal and opposite reaction).

 


Straw Rocket Launch Experiment

My one year old daughter playing with her straw rocket

This activity is ideal for toddlers. It requires some patience during preparation and an attention span long enough to hear the instructions on how to assemble and launch the rocket. I recommend this activity for kids ages 3+. However, my 1 year old did participate by playing with the straws and laughing with us.

Materials needed:

  • Construction paper
  • Scissors
  • Jumbo straw (~1/4″ diameter)
  • Tape
  • Glue dots or glue or tape (any strong, sticky material to attach the paper rocket to the straw)
  • Standard bendy straw (~1/8″ diameter)

Safety:

  • Make sure you have a clear open area for the rocket launch so nothing will obstruct the rocket (and cause toddler meltdown).
  • Safety goggles are a good idea if you have them. It will protect your child’s eyes from potentially getting poked by falling rocket tips.
  • Talk to your child about not shooting the rocket at people (especially faces, where eyes could be poked and injured). This is especially a risk if there is a younger sibling involved (I’ve learned from experience…). 🙂

Procedure:

  1. Cut a rocket ship shape out of the construction paper (print a template online or free hand it!)
  2. You may also let your child decorate the rocket with stickers, stamps, markers, etc to add more fun and toddler involvement into the rocket preparation.This is also a good way to demonstrate Newton’s second law…stickers increase the mass of the rocket and will slow down its acceleration. You can test this by cutting 2 of identical rockets from the paper, and then add stickers to one rocket and not the other.
  3. Cut the jumbo straw in half and tape closed one end of the straw.
  4. Attach the rocket firmly to the jumbo straw using glue dots, glue or tape – whichever of these you have on hand (the open end of the straw is at the bottom of the rocket).
  5. Stick the long end of your bendy straw inside the jumbo straw (as pictured below).
  6. Give the assembled rocket to your toddler and instruct them to blow into the short end of the bendy straw at the end of a countdown, like a rocket launch: “3, 2, 1, blast off!”
  7. Take a slow-motion video of the rocket launch and enjoy watching it together!

What happened:

Your child blew air (pressure) into the bendy straw resulting in a force on the rocket ship (force = pressure x area of straw). This force entered the closed chamber in the jumbo straw (attached to the rocket). When this force became greater than gravity the rocket launched!

I hope you and your child create as many happy memories as my kids and I did during this fun STEM activity (and don’t forget to take the slow motion video – they’re hilarious!).

 

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