I'm having a debate with a coworker and he says that if you have 2 water bottles, one full and one empty that the full one will hit the ground first if dropped at the same height. I said that weight does not effect air resistance and that the 2 bottles have the same drag. Therefore they will hit the ground at the same time. He also says that mass and weight are the same thing... which one of us is correct?
Picture is of the eclipse I took in NY using a window to make 2 reflections of the sun.
Just go outside and drop 2 water bottles you dingus.
We did and he said the full one hit first, to me it looked like he let go of it first
The earth is attracted more to the full bottle so it will hit the ground first, but the difference is negligible.
If air resistance is the same why would it matter? Also if one of the bottles begins to fall at an angle would that make the one that continues straight hit first?
>If air resistance is the same why would it matter?
What does air resistance have to do with the fact that the Earth is being attracted more towards the full bottle?
>Also if one of the bottles begins to fall at an angle would that make the one that continues straight hit first?
What do you mean by fall at an angle you impart some fierce perpendicular to gravity? Yes that might change the answer since the bottle will have to fall longer due to the curve of the earth. Again though, this effect is negligible unless you are making the bottle fly a long distance.
I know that if you drop 2 things in a vacuum regardless weight, or size/area. They fall at the same rate, so if 2 things with the same size/area but 2 different weights air resistance will be the same. So would 1:1 be the same as 0:0?
You're not listening to what I'm saying. Even in a vacuum, if one object has higher weight the Earth will move more towards that object, resulting in a negligibly shorter trip for that object. This it will hit the Earth first.
Wouldn't the object move towards the earth instead of vice versa since the earth has more mass?
But it would be basically the same right? That's my argument
Weight is proportional to mass, and so the full water bottle has a greater weight force than the empty bottle. The acceleration due to weight does not change with mass though, as acceleration is inversely proportional to mass (and mass component in the acceleration equations is cancelled out).
The drag force is only affect by the surface of the object, and is not affected by the mass of the object. However, because it is constant, two object with the same drag and different masses will experience different accelerations, with the heavier object experiencing less acceleration.
Because of this, the full water bottle experiences the same downwards acceleration as the empty bottle, but less upwards acceleration, making it fall faster.
Their drag coefficients are the same since they are externally identical, and so the upwards drag force will be the same for any given velocity
F=m*a => a=f/m
Therefore the bottle with greater mass will decelerate less due to drag for an overall greater downwards acceleration
Consequently the full bottle hits the ground first
But is the difference still fairly negligible?
Only if the factors involved are negligible but that's not what the question was now was it
Drop it from a tower and the difference should be obvious
So I'm wrong.... I can't let him know this though.
Thanks Veeky Forums!
I don't think weight is part of what determines the drag force. Here's a snapshot of the relevant section from wikipedia. When they say the density of the "fluid" in this case that means the air. The other factors in the equation besides the air density are speed of the object and stuff about the object's size and shape.
If that drag force wasn't there (or is so small that you can ignore it for all practical purposes) then two objects will hit the ground at the same time.
With the full water bottle the drag force is tiny but with the empty one it might be affecting it a little, causing it to hit the ground slightly later than the full one.
If you want to demonstrate two objects hitting the ground at the same time, try a pebble vs. a huge boulder. Neither of those will be affected by air drag too much.
Also weight =/= mass. Mass is measured in kg and an intrinsic property of the object. Weight is the force of gravity acting on a mass. weight=mass*g where g is gravity on the Earth. Our weight on a scale is a measure of how strongly Earth is pulling our intrinsic mass down. Your weight on another planet would be different, but your mass would be the same.
dropping from arm height would be hard to tell the difference. but a slightly higher height of drop, i'm guessing the magnus effect would start pulling and pushing the non-filled water bottle around and take away it's downward velocity. the filled bottle would be more resistant to extreme direction changes from magnus effect and hit the ground sooner. i'd bet if you set up a high speed camera and make sure you drop both bottles from the same height at the same time, you'll see the filled bottle hit ground first.
If they tumble due to.wind or some other factor, could the change in trajectory cause one to hit before another? I assume the lighter one would be more affected by this. If you took that variable out would the difference be relatively small?
Just a /b/tard here don't take my advice
The object is moving towards the Earth and the Earth is moving towards the object. That's how gravity works.
this is a good explanation.
I didn't mean to get into semantics but thanks
F=ma
Drag force is the same for both bottles. The drag force in the lighter bottle is able to decelerate it more because it has less mass.
Ezpz
Lieing by omission is a sin.
It has higher weight because the mass is larger. The acceleration is the same in each case.
F = Gmm/r^2 = ma
In the case of the force between a bottle and earth, the mass of the bottle cancels. Mass has nothing to do with motion in a vacuum.
Air resistance is not negligible with this kind of experience if you drop the bottle at 2 meters height. An empty water bottle can be really light and the air resistance can be important compared to the full bottle.