How many pennies does it take to get an apple up the inclined plane? This is the question my 8-year old set out to answer the other day.
In the last year, we have done a lot of inclined plane experiments. It’s a great way to learn about gravity and motion, easy to set up and something kids enjoy doing over and over again. We have already used the inclined plane to experiment with getting trucks, trains, LEGO bricks, rice, balls, and sand UP or DOWN. Now that apples are everywhere, they provided a new inspiration.
How many pennies does it take to get an apple up the inclined plane?
What you need
Books (to create an incline)
A board (a closet shelf works for us)
A yogurt container or a plastic cup for pennies
An apple (maybe even a couple of apples of different size)
Lots of pennies
A rubber band (it will go around an apple)
Hole puncher or scissors to make holes in the containers
Paper and pen to record observations
1.Poke two holes on two opposite sites of your yogurt container or plastic cup.
2. Thread a string through the holes and tie it security. Your container should look like a little bucket with a handle. 3. Put a rubber band on the apple (so you can connect it to a string). You might have to experiment with a couple of different rubber bands until you find just the right fit.
4. Tie a longish string connecting plastic container and apple.
Five books Incline
We started by making predictions. My 8-year old said that it would take100 pennies to take our apple up the incline of 5 books. My 5-year old said, “175 pennies!” And I said – 50. Who got the closest to the right answer? Read on to find out.
As you can see in the pic above, (1) we put five books under one end of a board. (2) Hung plastic container over the edge of the board. And (3) set an apple near the other end of the board.
The accuracy of this experiment increases dramatically if you eat an apple while performing it!
Start putting pennies into the container counting out loud.
At what count the car inched up? How many pennies did it take to get it all the way up?
So How many pennies did it take to get OUR apple up an incline? In our experiment, it took 63 pennies to get our apple to move a bit and 108 to get it all the way up the ramp. Your answer would depend on the size and density of your apple and the steepness of your incline.
It’s hard to believe, but in this fun experiment, kids learn a lot about physics through hands-on investigation. Friction, force, gravity, ramp, the angle of slope, motion, distance are all involved in this simple setup.
Some additional investigation questions
- How changing the angle of an incline by adding a book (or taking one away) would change the number of pennies required?
- What if you replace pennies with quarters? Would it take less or more coins to do the job?
- How can the weight of the apple effect the experiment?
- My son also immediately wanted to reverse the experiment and find out how many pennies can an apple pull up the incline.
Some questions to ask after the experiment
- What are simple machines?
- How do they help people?
- Do you know the definition of the following words: friction, force, gravity, ramp, the angle of slope, motion, distance.
Use our Experiment Sheet to Record the results
If you looking for more Apple Fun check out our Ultimate Guide to Apple Activities