Directions: Use the information provided and your knowledge of Physical Science to answer the following questions. Show all work where necessary.
Directions: Use the information provided and your knowledge of Physical Science to answer the following questions. Show all work where necessary.
Students design a rubber band–powered car that must roll as far as possible down a smooth hallway. They wrap a rubber band around the rear axle, wind it up, and release. The stretched rubber band unwinds and makes the axle spin, turning the wheels.
They try different designs by changing:
how many winds of the rubber band they use,
the wheel size,
and how well the car rolls (axle friction, alignment).
The class challenge:
Apply scientific ideas about energy conversion to design, test, and refine a car that converts stored elastic energy into motion energy.
A rubber band–powered car is an example of how stored energy can be converted into motion. When you stretch and wind the rubber band, you give it elastic potential energy. The more you wind it, the more energy is stored. When the car is released, the rubber band unwinds and pulls on the axle. This converts the stored energy into motion energy that makes the wheels spin and the car roll forward.
Scientific ideas can help students improve their designs. If the wheels are too wobbly or the axles rub too much, some of the motion energy is wasted as heat energy due to friction. That means the car will not travel as far. Larger wheels may help the car cover more distance with each turn, but they may also be heavier. The number of winds also matters: too few winds and the car doesn’t go far; too many and the rubber band might jam or twist poorly.
By testing different numbers of winds and wheel sizes, students can measure how far the car travels. They then refine their designs using data, making choices that help the car convert more of the stored elastic energy into useful motion energy.
Trial | Number of Winds | Distance Traveled (m) |
|---|---|---|
1 | 5 | 2.1 |
2 | 10 | 4.3 |
3 | 15 | 5 |
Design Version | Wheel Size Description | Distance Traveled (m) |
|---|---|---|
Car A | Small bottle-cap wheels | 3.2 |
Car B | Medium CD wheels | 4.3 |
Car C | Large foam wheels | 3.9 |
Look at Table 1. How does the distance traveled change as the number of winds increases from 5 to 15?
Which number of rubber band winds allows the car to travel the farthest distance?
Using Figure 1, describe the pattern between the number of winds and the distance traveled.
Why does the car with 5 winds travel the shortest distance, even though the rubber band is still stretched?
Which piece of evidence best shows that design choices affect how well energy is converted into motion?
How did changing the number of winds and the wheel size help students apply scientific ideas to design and improve a car that converts stored elastic energy into motion energy?
Claim:
Evidence:
Reasoning: