You hang up a feather in a special room. After the oxygen has been pumped out of the room, you release it. After a free fall of 2,25 seconds the feather hits the floor. **Calculate the height of the fall**. A bit afterwards you allow oxygen back into the room. You now hang up a bowling ball. The underside of the ball hangs at the same height as the feather of the previous experiment. You calculate the speed of the bowling ball hitting the floor. **Is the speed greater, lesser or equal to the speed of the feather hitting the floor?**

Guest Jan 10, 2020

#1**+1 **

When you say oxygen, I assume you really mean all gasses.

So the feather is falling in a vacuum and the bowling bowl is falling where there is air resistance.

I think the ball would fall more slowly.

Melody Jan 10, 2020

#2**+1 **

Sorry I don't really know all the correct English terms in physics, but yes that's basically it :) It seemed more obvious to me that a feather would fall slower since well... it's a feather. But this also makes a lot of sense! I don't really have an idea on how to calculate the height since I only know the duration of the free fall but maybe someone else will come along and help me :D

Guest Jan 10, 2020

#3**+1 **

I do not know if you are supposed to do this with calculus or with physics formulas.

I usually use calculus

If you say up is positive direction then

acceleration = gravity = -9.8m/s^2

Initial speed is 0

initial height is h

After 2.25 secs the father falls h metres and is at a height of 0.

\(\ddot{x}=-9.8m/s^2\\ \dot{x}=-9.8t\;m/sec\\ x=\frac{-9.8t^2}{2}+h\;metres\\ when\;\;t=2.25\;\;x=0\\ 0=\frac{-9.8*2.25^2}{2}+h\\ 0=-24.80625+h\\ h=24.80625 metres.\)

If the feather was in a room full of air then I think it would drop a lot more slowly because of the air resistence.

I am not good at Physics but that sounds right to me.

Melody Jan 10, 2020