Science Buddies: "Ask an Expert"

Hi, I am posting the following from my son:

I am in 7th grade and for my science fair project, I need a way to measure the force on a dropped object when it hits the ground. What I am trying to determine is which packing materials provide the best protection for an object in a collision. So I am planning on dropping containers filled with different packing materials surrounding some sort of force-measuring device in the middle. But I don't know how to either obtain or construct the force-measuring device.

Because I am measuring the effectiveness of the packing material, I need to measure the force inside. One method I thought about was having a metal ball sitting on top of clay. After hitting the ground, the ball will dig into the clay. I can measure how deep the impact is and assume that the deeper the hole, the greater the force. But I am not sure if this will work.

Does anyone have any suggestions on how to measure the force? (Either help with my suggestion or something else entirely.)

Hello, garylilia,

Are these what you're looking for? http://www.industrial-needs.com/measuri ... evices.htm. I ran a Google search on "force measuring devices" and that's the first link that came up, so you may want to do a little research through other sites.

Also, the idea with the metal ball and clay sounds really interesting! It has both quantitative (metric measurements) and qualitative aspects (you can take pictures or just visually compare the hole sizes) that you can use to your advantage. As to whether or not it'll work, there's just one thing I'm uncertain about, which is the hardness of the clay. If it's too hard, the impacts won't be easy to compare, and might even be minimal. But try it for one or two packing containers and let me know what happens!

Hope this helps!

I just ran across a gadget that might help, see

http://www.drypak.com/shippingHandlingIndicators.html

Good luck