Can someone explain the Hammer-Feather experiment?

Question

I'm in my final year at secondary school and have done this twice throughout my science lessons (over 5 years) and I want it explained in simple terms but with enough detail for a GCSE Physics course. Its the experiment where a hammer and feather are dropped in a vacuum and they hit the floor simultaneously.

Answer 1

The most important principle behind the hammer-feather experiment is that gravity acts with nearly the same force on objects of different masses.



When a feather is dropped in atmosphere (in the presence of the amount of air found on Earth), it doesn't fall slowly because it has a small mass. It falls slowly because it has a large surface area compared to its mass. As the feather falls towards the ground, millions of air particles "bump" into the feather and slow it's descent.



The same thing happens with a hammer. Millions of air particles also "bump" into the hammer, but they don't slow the hammer as much because it has a much greater mass.



When air is taken away (as it is in a vacuum), there is only one force (gravity) acting on the feather and hammer as they fall. The "bumping" of the air particles doesn't happen, so the feather is not slowed down as it is in the atmosphere.



Now, going back to what I said in the first paragraph: since gravity acts on the hammer and feather with a nearly identical amount of force, they will both fall at the same velocity in a vacuum.



Hope this helps.

Answer 2

In space (vacuum), there are no gases/air. So there is no wind resistance.



Newton's law of gravity states that the speed of which something falls is independent of its weight. In a vacuum, both a feather and sledgehammer falls at the same right.



But with air resistance, a hammer drops first as its weight displaces more gas particles more quickly than a feather.

Answer 3

The inertial mass of an object is identical to its gravitational mass..so F=ma=W=mg..>a=g=const..ie in vacuo objects fall at same rate indep of mass The ratio of mass/surface area is smaller for the feather. Air resistance varies as surface area. Therefore the feather experiences greater air resistance in proportion to its weight..more drag..less acceleration.

Answer 4

Info I found:

http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_15_feather_drop.html

and a video of the experiment:

http://www.unexplained-mysteries.com/viewvideo.php?id=PE81zGhnb0w&tid=122971

Maybe that will help.