![]() Many students will agree that the force of air resistance on a moving object depends on the speed of the object. Factors suggested by students might include shape, mass, speed, or position or orientation of the object. Ask students what factors determine the extent to which air resistance affects the movement of a moving object. The warm-up activities with the paper and the book, the coin and the feather, and the video of Commander Scott dropping a hammer and a feather on the moon all demonstrate that the difference in the rate of falling objects depends more on the effects of air resistance than on the rate at which gravity accelerates falling objects. Galileo’s actual experiments involved rolling spheres with different masses down a long incline in order to slow their motion and allow him to record data for his calculations. It is not clear if that story is true, but it is known that Galileo did perform experiments to show that falling objects, regardless of mass, accelerate toward Earth at the same rate. Several hundred years before Commander Scott performed his experiment on the moon, Italian physicist and mathematician Galileo Galilei supposedly dropped 2 cannon balls of different masses from the Leaning Tower of Pisa to prove that they would fall at the same rate. If someone on the surface of Earth dropped a hammer and a feather from the same height at the same time, the hammer would tend to fall faster, landing sooner on the ground.Ī much earlier experiment is said to have happened in the 16th century. This event seems to contradict experience. A quick Internet search will turn up footage of Commander Scott dropping a hammer and a feather simultaneously on the surface of the moon. In 1971 David Scott, an astronaut on the Apollo 15 mission, performed an experiment while standing on the moon. This time the coin and the feather fall at the same rate, landing on the bottom end of the tube at the same time.Īnother warm-up activity for a lesson in air resistance might include a review of some famous experiments involving falling objects. Once a vacuum is created inside the tube, close the valve and repeat the experiment. A valve on 1 end of the tube allows you to remove the air in the tube with a vacuum pump. The coin falls from 1 end of the tube to the other, while the feather floats slowly down. Hold the tube upright and then invert it. In this demonstration you place a coin and a feather in a long, clear tube. Then drop the 2 objects together and they should fall at the same rate.Īnother standard demonstration in air resistance is the coin and feather. Repeat the experiment, first placing the paper on top of the book so that the paper is shielded from the air by the book. If the book and the paper are held separately and dropped, this will be the case. Many students will likely select the book. Hold up both objects and ask students which will fall to the floor faster. ![]() One common demonstration of air resistance involves observing a piece of paper and a heavy book as they fall. Introductory-level physics courses often use situations with ideal conditions to introduce students to the fundamentals of mechanics, and air resistance is included in later courses.Īir resistance is an important concept for students to understand, and there are some simple demonstrations and activities that allow students to investigate the effects of drag on moving objects. One reason is because calculations that involve air resistance can be challenging. ![]() However, in most first-year physics classes, air resistance is ignored. The trajectory of projectiles, the velocity of falling objects, and the design of modern vehicles are just a few instances where air resistance affects the movement of an object. Product Management Coordinator for Physical ScienceĪir resistance can be a significant factor in many practical applications. ![]()
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