Today, we’ll take a closer look at angles, mass, and the forces of friction to explore how they affect cars. Before beginning, you may also want to read Energy: Physical Science for Kids.
All objects require energy to move. This is Isaac Newton’s first law of motion: An object at rest (or in motion) will stay at rest (or in motion) unless it is acted upon by a force (which gives it energy). (source) This is pretty easy to prove: Put a toy car or ball on a flat surface. If the surface is flat and nothing touches it, it won’t move! Let’s learn more about some of these forces with three simple STEM experiments.
Experiment #1: Ramps and angles
What you need:
- 1 toy car (or build it with LEGO or similar blocks)
- 1 ramp, about 12 inches long (can be made from wood planks, large books, or any sturdy material)
- blocks or other objects to prop ramp on
- tape measure
- protractor
What to do:
Begin by printing our tracking sheets. If you were with us for our Level 2: Snow Unit, your child may remember what you learned about acute, right, and obtuse angles. Review that information at the top. Introduce your child to the protractor and explain how it helps us to measure angles, which are measured in degrees.
Next, set up your first angle at 45 degrees, demonstrating how to do this with the protractor. Take your first car and let it roll down the ramp (careful not to push or add any additional force). When it stops, measure the distance. Record the angle (45 degrees) and distance on your tracking sheet.
Next, repeat the experiment with two different angles and record the different distances. Does a bigger or smaller angle cause the car to go farther? Which angle creates more energy?
Explanation: The bigger the angle, the higher the ramp. The higher the ramp, the greater the Gravitational Potential Energy (GPE) and the more force put on the car. So the higher the GPE, the farther we expect the car to go.
Experiment #2: Weight and energy
How does the weight of an object affect how much energy it needs to move? Let’s find out with this activity.
What you need:
- a toy car (or build it with LEGO)
- a ramp, about 12 inches long (can be made from wood planks, large books, or any sturdy material)
- blocks or other objects to prop ramps on
- a small kitchen scale (optional, but helpful for making more exact recordings)
- tape measure
What to do:
Begin by setting up your ramp at your desired angle (45 degrees works fine). Weigh your car, and record the weight on our printable. Next, send the car down the ramp and record the distance.
Next, let’s add some weight! If you build your car out of LEGO or similar blocks, add a few more. If you are using a regular toy car, add more weight by attaching some small rocks or pennies with play dough or tape. Weigh the car again and record the weight. Next, send it down the ramp and record the distance.
Repeat this two more times, adding more weight each time. Next, review your findings. Did the heavier or lighter car go farther?
Explanation: The lighter car should roll further because it requires less GPE to roll the same distance as the heavier car. It takes more energy to move a heavier object than a lighter one, which they have likely noticed when they try to lift something heavy versus something small.
Experiment #3: Friction and distance
If an object in motion stays in motion, as Mr. Newton says, why doesn’t our car keep rolling forever? This is because an invisible force is acting on the car, slowing it down—friction! We experience friction all the time. For example, drag your hand along a smooth surface. If you press hard, your hand sort of bumps along the surface. That’s friction in action! Let’s see how friction affects our car.
What you need:
- a toy car (or build it with LEGO)
- a ramp, about 12 inches long (can be made from wood planks, large books, or any sturdy material)
- blocks or other objects to prop ramps on
- 3-4 different surfaces, (something smooth, something rough, and something in between. examples include: wood floor, a carpet, a towel, tile floor, grass, etc.)
- tape measure
What to do:
You can use the same ramp set up from the previous experiment. Set up the ramp on your first surface, recording what the surface is in your printable. Next, let the car roll and measure how far it goes.
Repeat the experiment on your different surfaces, recording your findings each time.
Which surface did the car roll the farthest on? Which surface slowed the car fastest?
Explanation: Rougher surfaces have more friction between them. The more friction that exists, the more energy needed to resist and overcome that force.
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