A tennis ball drops from rest at the top of a tall glass cylinder—first with the air pumped out of the cylinder so that there is no air resistance, and again after the air has been read-mitted to the cylinder. You examine multiflash photographs of the two drops. Can you tell which photo belongs to which drop? If so, how?
Solution to 25DQ. Step 1 When there is no air resistance, the body is said to be in free fall. The acceleration of the tennis ball freely falling will be nearly equal to acceleration due to gravity. A multiflash photo of a tennis ball falling over top of a glass cylinder without air shows that, the tennis ball will move farther in each successive interval. Thus it tells that the tennis ball is accelerating. At the top of the multiflash photo, the ball will be closely placed and at the bottom, it will be placed at larger distance.