A pendulum painting machine turns science into art by letting a swinging cup or bottle drip paint onto paper below. As the container moves back and forth, gravity and inertia guide the paint into loops, spirals, and curves. This project is useful because it helps students see motion, patterns, and forces in a creative way.
It also encourages careful building, testing, observing, and improving a design.
The machine works by hanging a paint container from a string so it can swing freely like a pendulum. When the container is pulled to the side and released, it speeds up near the middle and slows down near the ends of its path. The paint falls while the container moves, so the drawing records the pendulum's motion over time.
Changing the string length, starting angle, paint thickness, or hole size changes the pattern on the paper.
Key Facts
- A simple pendulum is a mass hanging from a pivot by a string or cord.
- The period is the time for one full back-and-forth swing.
- For small swings, T = 2π√(L/g), where T is period, L is string length, and g is gravitational acceleration.
- Longer strings make slower swings, while shorter strings make faster swings.
- Gravity pulls the pendulum downward, and tension in the string keeps it moving in an arc.
- Paint patterns change when you change variables such as string length, release angle, paint thickness, hole size, or paper position.
Vocabulary
- Pendulum
- A pendulum is an object that swings back and forth from a fixed point.
- Period
- The period is the time it takes for a pendulum to complete one full swing cycle.
- Amplitude
- Amplitude is the size of the swing, measured by how far the pendulum moves away from its resting position.
- Gravity
- Gravity is the force that pulls objects toward Earth and helps bring the pendulum back downward.
- Variable
- A variable is something you can change in an experiment to see how it affects the result.
Common Mistakes to Avoid
- Making the paint too thick. Thick paint may clog the hole and stop the steady dripping needed to show the motion pattern.
- Using a weak support frame. A wobbly frame changes the swing and can spill paint, so the stand should be stable before testing.
- Pushing the pendulum instead of releasing it. A push adds extra force and makes trials harder to compare, so pull it back and let go gently.
- Changing too many things at once. If string length, paint thickness, and release angle all change together, it is hard to tell which variable caused the new pattern.
Practice Questions
- 1 A pendulum painting machine has a string length of 0.25 m. Using g = 9.8 m/s² and T = 2π√(L/g), estimate the period of one full swing.
- 2 A pendulum completes 12 full swings in 18 seconds. What is its period in seconds per swing?
- 3 Two students use the same paint and paper, but one uses a much longer string. Explain how the pattern and motion might change, and why.