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Name: Laret
Status: educator
Grade: N/A
Location: CA
Country: N/A
Date: 5/20/2005


Question:
If two objects of different weights are dropped form the same height, which one will reach the ground first? Why? What is the scientific explanation and how would I teach it to children?


Replies:
There is a classic physics experiment in which a feather is placed inside a sealed tube. The air is then pumped out of the tube. Next, the tube is turned upside down and the feather falls like a rock.

The acceleration of a falling object in a gravitational field is a constant. It does not depend on the weight, size, or shape of the object. What does depend on these factors (at least on the size and shape) is the drag (or resistance to motion) in the air. In the absence of air, all objects fall at the same rate. In the presence of air the object that is most stream-lined (for equal weights) or the heaviest object (for same shape and size) will hit first.

Greg Bradburn



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