prashant bharadwaj Posts: 1, Reputation: 1 New Member #1 Dec 16, 2006, 02:37 AM
Gravity
If 2 objects of different weight are thrown from equal height , which will reach the earth first, the heavier object or the lighter object, or both will reach at same time. :)
 Capuchin Posts: 5,255, Reputation: 656 Uber Member #2 Dec 16, 2006, 03:08 AM
Have you seen the video of a hammer and feather being dropped on the moon? They both hit the lunar surface at the same time!

Why is this?

Gravity? The moon has a gravitational force of about 1/6th the Earth. This makes things fall slower than they would on Earth, but doesn't affect how different objects would fall.

So why does the feather hit the ground the same time as the hammer?

Because there's no atmosphere on the moon! There's no air resistance to push against the force of gravity.

This is exactly the same case on earth. If these two objects are exactly the same shape, they will hit the ground at the same time. But we have an atmosphere, and this requires force to push through, you have to push all the air molecules out of the way.

Bigger objects have to push more air molecules out of the way for a given speed, so they are more likely to fall more slowly. Although it depends on the exact shapes.

If they are different shapes (you didn't specify) then one or the other will hit the ground first, dependent on which has the larger surface area and thus the slowest terminal velocity (Because there's more viscous resistance).

Indeed, if you evacuate a tube of air, and drop a feather and penny at the same time, we get the same result as on the moon.
It's nothing to do with gravity and all to do with air resistance! :)

Everything falls at ~9.8m/s/s on Earth if you disregard air resistance

I hope this is enough detail for you!
Thanks for the question :)
 Capuchin Posts: 5,255, Reputation: 656 Uber Member #3 Dec 16, 2006, 08:17 PM

Here's the video of them dropping a feather and hammer on the moon. No air resistance so they both hit the ground at the same time! :)
 SBowman Posts: 71, Reputation: 6 Junior Member #4 Jan 7, 2007, 07:53 PM
A funny piece of information - a bullet fired and it's casing will hit the ground at the same time. So when you fire a gun, and the case pops up from the back, when the casing hits the ground, the bullet will have hit the ground as well.
 Capuchin Posts: 5,255, Reputation: 656 Uber Member #5 Jan 8, 2007, 02:19 AM
Only if you fire horizontally... And if you fire horizontally you're probably shooting at a target - In which case the bullet doesn't hit the ground, or has richocheted at a different angle, and hits the ground at a different time. This is also assuming the case falls out the back of the gun, instead of being sprung out.

There are so many assumptions here, that it only really works for a theoretical gun ;)
 reubenkinara Posts: 10, Reputation: 1 New Member #6 Mar 25, 2010, 08:28 PM
Originally Posted by Capuchin
Have you seen the video of a hammer and feather being dropped on the moon? They both hit the lunar surface at the same time!

Why is this?

Gravity? The moon has a gravitational force of about 1/6th the Earth. This makes things fall slower than they would on Earth, but doesnt affect how different objects would fall.

So why does the feather hit the ground the same time as the hammer?

Because there's no atmosphere on the moon! There's no air resistance to push against the force of gravity.

This is exactly the same case on earth. If these two objects are exactly the same shape, they will hit the ground at the same time. But we have an atmosphere, and this requires force to push through, you have to push all the air molecules out of the way.

Bigger objects have to push more air molecules out of the way for a given speed, so they are more likely to fall more slowly. Although it depends on the exact shapes.

If they are different shapes (you didn't specify) then one or the other will hit the ground first, dependant on which has the larger surface area and thus the slowest terminal velocity (Because there's more viscous resistance).

Indeed, if you evacuate a tube of air, and drop a feather and penny at the same time, we get the same result as on the moon.
It's nothing to do with gravity and all to do with air resistance! :)

Everything falls at ~9.8m/s/s on Earth if you disregard air resistance

I hope this is enough detail for you!
Thanks for the question :)
I believe part of the reason. I believe that one of the particle/waves emitted by the sun is the graviton which pressurizes everything in its path. Now as long as mass is able to sustain itself under that pressure and does not implode It will move in a straight line however since earth a large planet warps the space/time around it the two bodies path is disrupted to they full toward the earth. Now the force acting upon the bodies (feather and penny) is equal to its inertia. Therefore they will fall at the same speed. And since there's no air resistance the feather will not drift.

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