Catapults!
Students observe the relationship between the angle of a catapult (a force measurement) and the flight of a cotton ball. They learn how Newton's second law of motion works by seeing directly that F = ma. When they pull the metal "arm" back further, thus applying a greater force to the cotton ball, it causes the cotton ball to travel faster and farther. Students also learn that objects of greater mass require more force to result in the same distance traveled by a lighter object.
Students make model catapults to explore Newton's second law of motion.Copyright National Institute of Standards and Technology http://www.itl.nist.gov/div898/handbook/pri/section4/gifs/catapul2.gif
Understanding the scientific concepts of Newton's laws of motion has made it possible for engineers to build airplanes that fly, elevators and amusement park rides that are exciting but safe, cars that drive safely at high speeds and structures that do not collapse. Aerospace engineers save fuel by exploiting the second law when they let the planet's force of gravity pull a spacecraft towards the planet to increase its velocity, and then steer the spacecraft away from crashing into the planet.
After this activity, students should be able to:
- Recognize that understanding the scientific concepts described by Newton's laws of motion enables engineers to design airplanes, amusement park rides, elevators, and much more.
- Use the catapult model to explore the force exerted on the cotton ball and graph the correlation between angle (force) and distance traveled (acceleration).
- Collect data throughout this experiment, including the maximum height of the cotton ball in flight and the distance traveled until it lands on the floor.
- Calculate the average of a data set.