Simple Science: Catapults and Trajectory

Our science studies have recently taken us into the field of physics, specifically trajectory. Trajectory is the path a free flying object (a projectile) follows through the air. A projectile has two forces working on it. The inertia that launches it into the air and the gravity that brings it back down to earth.

So how do you study trajectory? By hurling things into the air!

Learning about trajectory with catapults Education Possible

DIY Wooden Catapults

I found a great post at Housing a Forest showing how to make simple catapults and I knew we had to give them a try in our science lesson.

My husband took the wood we used for our lever experiments and cut it down to make catapults. He made a variety of sizes so we could see if the size of the catapult made a difference to the trajectory. Some had a longer arm and others had a slightly thicker base.

Hands-On Science Experiment

First everyone chose a small stuffed animal to launch. The kids put their animal on and stepped down on the other end. None of the animals traveled too far.

Learning about trajectory with catapults Education Possible

They decided to try again, this time increasing the force, by stepping harder. Some of animals moved further, especially for the bigger kids. One of the kids stepped so hard, he broke his in two!

second attempt stepping harder on catapult Education Possible

On the final attempt, the kids jumped or stepped onto their end of the catapult as hard as they could. This did send the animals the highest they had been, but it was still less than what everyone was expecting.

attempt three jumping on catapult Education Possible

What we learned

Trajectory is only changed by two things; the speed at which you launch the projectile and its angle during launch. When you increase or decrease the speed or angle during takeoff, the trajectory of the projectile will change.

Even though we had varied the catapult sizes slightly, there wasn’t really enough difference between them to launch the objects we had chosen off into higher trajectories.

By increasing the speed at which they were launched (by stepping on the board harder) some kids were able to lengthen the distance they flew. If we had also increased the angle of the wood, we probably would have seen a bigger difference in the path.

Since we couldn’t change the angle of the catapult, we decided to try it with a lighter object, a marshmallow. The kids followed the same steps as before, but had much better results. The decreased weight of the projectile was a much better match for the catapults we had.

catapulting marshmallows Education Possible

We just love bringing science to life. It’s one of the reasons we’ve all enjoyed using the Disney Imagineering Videos so much.

Do your kids love to send things into the air?

Megan Zechman
I love homeschooling! Learning is a way of life for our family. Most days you will find us exploring our Central Florida community, having fun while learning. I am constantly looking for new and interactive ways to engage my older children.
Megan Zechman
Megan Zechman


  1. Hi! Just popping in to say hello – the SITS Tribe Building Challenge started today and we’re ‘tribe mates’. Looking forward to getting to know you.

  2. Hi Megan, I really enjoyed this post. We did something like this a few weeks ago. I think we’ll try again, but this time we’ll change up the objects like you guys did. Looking forward to connecting more via our tribe.

    • Hi Darcel! I’m also looking forward to getting to know you. I’m glad you liked the post and I hope you have the success that we did by mixing up the projectiles. This was definitely a kid favorite!

  3. I am loving this experiment and how much you learned from the first unexpected results. Thanks for sharing with Afterschool!

    • Thank you Natalie. I was very surprised by our results. Luckily we had done another type of catapult as well that used small, light objects, so I had some substitutes for the stuffed animals. The kids really wanted to see their objects fly!!

  4. I love this idea! I’ve pinned it to my science board so I can remember it later. My daughter will love this!

    Stopping by to say to hi to a fellow Tribe member!

    • I’m glad you stopped by Tara! It was definitely one of our favorite experiments. The kids really loved launching things into the air! Thank you for pinning.

  5. Love this post! I featured it at the After School Linky today.

  6. oh this looks fun! Thanks for linking up at the Saturday Science Blog Hop & Link Up! I hope you stop by and link up again this week!

    • Thank you Samantha! We love doing fun experiments for science. This was one of our favorites! I’m glad we found your blog hop 🙂 I’m sure we’ll link up again soon.


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