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The other day I was watching my oldest son play with one of his toys, and I realized he was experimenting with different types of energy. His toy was a hot wheels track that clamped to a table on one end , and hung down on the other. When I saw my son playing, I realized this was an opportunity for an experiment! So I asked him, “What would happen if you changed the height of the track? Would the car stop closer or farther from the end of the track?” He shrugged his shoulders.
Exploring Energy for Kids: How Are Height and Distance Related?
To help my son find the answer my questions, I came up with a quick little experiment.
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Supplies:
 6 wooden blocks, approximately 5″ by 12″
 Long plank of wood
 Hot wheels track with clamp. My son used his Dino Spinout Track Set
 Extra hot wheels tracks
Experiment:

 Find six wooden blocks all about the same size.

 Use 4 blocks and a longer plank of wood to create the first height.

 Next, clamp the track onto the long plank of wood. Also, add length to the track as needed to make sure the track touches and runs along the floor a bit.

 Run a toy car down the track, and mark where it stops with a piece of tape.
 Add one block to each side to create a second height.
 Run the same car down the track, and mark where it stops with a piece of tape.
Here’s what we saw!
The second distance (the one with the highest starting point) was greater than the first distance! In other words, as the starting point of the car got higher, the car traveled farther.
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Do our results make sense?
The two types of energy my son was playing with were potential energy and kinetic energy. Potential Energy (or PE for short) is the energy stored in an object because of its height from the ground. Potential energy is expressed as:
PE=mgh
where m=mass
g=gravity
h=the object’s height from the ground
Kinetic Energy (or KE for short) is the energy in an object when it is moving. Kinetic energy is expressed as:
KE=½mv²
where m=mass
v=velocity (speed) of the object
According to the law of conservation of energy, energy can neither be created nor destroyed. Energy can, however, change forms. In the case of my son’s toy, the energy of the car was changing from potential to kinetic energy.
To guess the answer to the question I asked my son “What would happen if you changed the height of the track? Would the car stop closer or farther from the end of the track?”, let’s look at the math first:
Since energy can neither be created nor destroyed, then the energy the car has at the top of the track is equal to the energy the car has going down the track. In other words, the potential energy of the car is equal to its kinetic energy:
PE=KE
Substituting in the equation for each forms of energy, you get:
mgh=½mv²
Thinking about speed, how is it usually expressed? In miles per hour, or inches per second, right? In other words, speed is distance traveled (d, miles) divided by time (t, hour), or d/t .
So substituting in d/t for v, the equation changes to:
mgh=½m(d/t)²
or
mgh=½md²/t²
In the equation above, how does height (h) relate to distance (d)? Focusing on just the two variables we’re interest in (height and distance), you’ll see they relate to each other as follows:
h=d²
Height is directly related to distance. Directly related means that when one variable gets bigger, the other variable also gets bigger (or as one variable gets smaller, the other variable gets smaller). In our example, directly related means that as the starting point of the car gets higher, the car will travel farther, which is exactly what we saw!
And that is just another way kids’ toys can teach them engineering!
Looking for other ways to introduce you kids to engineering? Check out some of my other posts!
Tinker Crate: Circuits and Optics
Teach Your Kid to be a Reliability Engineer!
Teach Your Kid to be a Mechanical Engineer!
Teach Your Kid to be a Project Engineer!
Be a Process Engineer: Play “How’s it Made?”
Learn about Forces at the Splash Park!
An Explosive View of a Dinosaur
10 Books that Inspire Kids to be Engineers
Toys that Teach Engineering
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Wow your kids are lucky to have a Mum who understands engineering and what a great way to teach them. It’s so clever to use the toys as an opportunity to help them understand.
Thank you! The principles are pretty simple when you’re just looking for the relations, and don’t get bogged down in the math.
This is pretty cool! I’ll have to save this experiment for the next time I am nannying! The kids will get a kick out of it.
I love this! My sister and I did the same type of experiments as children! It’s fun to see what happens with each change you make or how each toy car reacts.
Isn’t it funny how all kids love to experiment? I guess there’s a little engineer in all of us…
My goodness this brought me back to science class! So fascinating!
Coming Up Roses
Lol! I’m glad it brought back (hopefully fond) memories!
We all have lessons around us. Keeping our eyes open to possiblities like kids keeps us young and still learning. Great post and thank you for sharing.
I’m glad you liked it!
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