How to determine air-resitance for a dropped coin

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In summary, the conversation is discussing how to determine air resistance for a coin being dropped from 2 meters onto a concrete floor. It is mentioned that Mythbusters did an episode on this and measured the terminal velocity, which can be used to find the drag coefficient. However, it is also noted that in reality, drag will not significantly impact the coin's trajectory as it hits the ground in about 2/3 of a second. It is argued that the difficulty lies in the coin flipping over and over, causing different surfaces to face the ground and varying levels of resistance.
  • #1
16physicist
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Can anyone tell me how I can determine air-resitance for a coin being dropped from 2 meters onto a concrete floor?

Thanks a lot.

-Arash Ay
 
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  • #2
Depends on what, exactly, you are looking do figure out. Mythbusters did an episode on this, iirc, where they actually measured the terminal velocity, so you could take that and plug it into the terminal velocity equation to find the drag coefficient.

Realistically, though, when dropped from 2 meters, drag will play an insignificant role in what happens. The coin hits the ground in about 2/3 of a second, traveling at 6.5 m/s. The terminal velocity, on the other hand, is probably somwhere around 40 m/s.
 
  • #3
This would be very difficult because when the coin is dropped it will flip over and over so the same surface will not always be facing the ground. When the flat side is down the resistance will be more than when the thin edge is facing down. But like Russ said it would be so small and would not make much difference.
 
  • #4
Okay, I apperciate that, thank you.
 

1. How does the size of the coin affect its air resistance?

The size of the coin does affect its air resistance. Generally, larger coins will have a higher air resistance because they have a larger surface area for air to push against. However, other factors such as the shape and weight of the coin also play a role.

2. How does the height from which the coin is dropped affect its air resistance?

The height from which the coin is dropped does not directly affect its air resistance. However, a higher drop height will result in a higher velocity for the coin, which will in turn increase the air resistance. This is because air resistance is dependent on the velocity of the object.

3. Is air resistance the same for all types of coins?

No, air resistance is not the same for all types of coins. Different coins have different shapes, sizes, and weights, which will affect their air resistance. For example, a coin with a larger surface area will experience more air resistance than a coin with a smaller surface area.

4. Can air resistance be measured for a dropped coin?

Yes, air resistance can be measured for a dropped coin. This can be done by using a high-speed camera to record the coin's descent and analyzing the footage to calculate the acceleration and velocity of the coin. From there, the air resistance can be determined using Newton's second law of motion.

5. How can air resistance be minimized for a dropped coin?

To minimize air resistance for a dropped coin, one can use a coin with a smaller surface area, such as a smaller or thinner coin. Additionally, dropping the coin in a vacuum or still air will also reduce the effects of air resistance. However, it is impossible to completely eliminate air resistance for a dropped object.

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