One of my son’s birthday presents this year was a remote control car. After playing with my son for awhile, my husband decided he wanted to have one too, so they could play at the same time. But he didn’t just go buy a cheap little remote control car. He bought a hobby grade remote control car! Once my son saw how cool his dad’s car could do, he decided to save his money, sell some toys, and do some extra chores around the house so he could buy one himself. When one of the parts broke on his remote control car, we were able to teach him about materials engineers!
Teach your kid to be a Materials Engineer!
The other day my husband and son were playing with their RC Cars again, and one of the cars suddenly stopped moving! My husband picked it up, and turned the controller to see if the wheels would move. Instead of movement all he got was a loud grinding noise! So they headed inside to figure out what was going on.
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Once they removed the top of the car, they saw exactly what the problem was: one of the teeth of the gear connected to the rear axle had been sheared off.
The reason the gear had sheared? Dissimilar materials. The gear pictured above was made out of plastic, while the gear it was touching was made of metal.
We talked to our some about the differences in the materials.
Husband: Can you scratch the plastic gear?
Son: (my son takes a pair of scissors and scratches one of the remaining teeth) Yes.
Husband: Can you scratch the metal gear?
Son: (my son tries to scratch the metal gear with the scissors) No.
Husband: Right! That’s because the metal is harder than the plastic gear.
Hardness is the measure of how resistant an object’s material is to being broken due to friction from another object’s material. There are various tests that can be performed on a material to get a “hardness” measurement. In this case, we simply noticed that my son was able to scratch the plastic, but was not able to scratch the metal. This told us that the plastic was not as hard as the metal.
When materials of difference hardnesses are put into repetitive motion (like two gears going around and around to make an axle rotate), the harder material will eventually break the softer material.
So how did my husband and son fix it?
First, using q-tips, my son cleaned out all the bits of the gear that had broken off. Leaving all those broken off parts would end up destroying any replacement gear they put back in once they played with the car again.
Next they needed to replace the broken gear. Instead of replacing the broken plastic gear with another plastic gear, they decided to replace it with a metal one. That way the two gears would be made of the same material, and would have the same hardness!
After they put everything back together, they headed back outside for more fun!
And that’s how we’re teaching our son about being a materials engineer!
Interested in what kind of Engineer you should be? Take my quiz and find out!
Interested in other ways to teach your kids about engineering? Check out some of my other posts!
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Teach Your Kid to be a Mechanical Engineer!
Teach Your Kid to be a Project Engineer!
Teach Your Kid to be a Reliability Engineer!
Be a Process Engineer: Play “How’s it Made?”
Learn about Forces at the Splash Park!
Exploring Energy: How are Height and Distance Related?
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10 Books that Inspire Kids to be Engineers
Toys that Teach Engineering