Fiddling around with the physics behind the BBC person Universe video clip of a bowling ball and also a feather gift dropped in a vacuum chamber.

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Dropping things can be fun. Dropping things in a vacuum is even cooler. You can think that dropping points in a large vacuum chamber would be the can be fried in coolness. Well, it's close. In fact, this is the ideal feather and also heavy object dropping video.

Yes, astronaut David Scott dropped a hammer and also feather in a much bigger vacuum room - the moon.

Heavier Objects Don't fight the floor First

I've already covered the typical ideas about dropping objects. In general, most human being think that more heavier objects should autumn faster than lighter objects. Really, what they typical is that heavier objects should loss with a greater acceleration than light objects, yet they choose to speak "faster".

Here is the short answer.

If over there is no wait resistance, after friend let walk of an object the only pressure on that is the gravitational force.The gravitational force is proportional to the massive of the object. More massive objects have a greater gravitational force.The acceleration of an item is proportional to the net pressure on the object and inversely proportional to the fixed of the object.


See. The masses cancel. Mass doesn't matter also though issue is do of massive (physics pun). Also, I composed these equations as scalar rather of vectors simply to do it watch simpler.

The Bowling Ball and Feather in real Speed

The bowling ball and also feather autumn in the BBC person Universe video clip looks awesome. However, they ran the shooting in slow movement to do it look more dramatic. Wouldn't in be cool to view it in real time? ns think I can make that happen.

Normally, I would take a video like this and also find the real frame rate. I've done this before with several of the MythBusters videos. The simple idea is come look at a falling object. Since you know the acceleration must be -9.8 m/s2, you have the right to just uncover the correct framework rate to give you the acceleration. It's quite simple. However, that doesn't occupational in this case. The difficulty here is the there room two points I don't know. Ns don't recognize the distance scale and I don't recognize the framework rate. This means I need another strategy.

Luckily, the video clip shows the same bowling ball and also feather dropping through air and in genuine time. I have the right to use the to find the scale of the video. In this case, i will usage the close increase shot that shows the bowling ball and also I will discover the diameter.

If I use a bowling sphere diameter the 21.59 cm, the falling ball appears to have actually the correct acceleration. Below is a plot the the vertical activity of that an initial fall.


Of food this is utilizing the cost-free video analysis program Tracker. Also, remember that the kinematic equation for things with a constant acceleration (in the y-direction) is:


The ax in front of t2 in the installation equation would certainly be 1/2 of the acceleration. So, a coefficient of -4.73 would offer an acceleration of 9.46 m/s2. This isn't 9.8 m/s2 choose I would certainly expect, however it's close enough.

I can likewise get the complete falling time indigenous the video clip with a worth of 2.04 seconds. This means that I deserve to solve for the drop height of the ball.


However, i ignored the waiting resistance top top the bowling ball during this drop. Is that ok? Let's speak the ball has a mass of 6 kg. If you then produce a number calculation for a falling sphere both with and also without air resistance, you get a time distinction of just 0.048 seconds. Yes, girlfriend can shot this calculation for you yourself (as a homework exercise).

Moving on to the slow-moving motion video (without air), I acquire the adhering to plot because that the vertical place of the bowling ball.


This provides an acceleration that 0.018 m/s2 - however that's not a actual second, that's a fake second (since the video clip isn't in real time). If I contact this time unit s', ns can set this acceleration same to 9.8 m/s2 (real seconds here) and also solve for the relationship between real and fake time.

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This way the sluggish motion video clip would have to be tape-recorded at 580 frames per 2nd instead the 25 frames per second. Perfect. Now I just need to rise the speed. Here's what that would look like.