IGCSE Pressure Question: How many balloons can be inflated?

In summary, the conversation discusses a problem involving inflating balloons with a helium cylinder. The volume and pressure of the helium are given, along with the volume and pressure of each balloon. There is a discrepancy between the answer provided and the mark scheme, and discussion ensues regarding the final pressure in the cylinder and the movement of the last of the gas to the balloons.
  • #1
UnknownGuy
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Hi, very quick question... It does like this: Helium in a cylinder (Which will be used to inflate a number of balloons) has a volume of (6*10-3) cubic meters and a pressure of (2.75*106)Pa. The pressure in each of the helium balloons is (1.1*105)Pa, and the volume of each balloon (3*10^-3) cubic meters.The temperature of helium does not change. How many balloons were inflated?

-How i solved it: Pressure * Volume = Constant so... (6.0*10^-3)*(2.75*10^6)=V2*1.1*10^5... V2= 0.15m3... Now what i did here was divide the total volume of helium at 1.1*105 by the volume of helium in each balloon and so...0.15/3*10-3... My answer was 50 balloons.

-Mark scheme has the following answer: (0.15-(6*10-3))/3*10-3... Can someone tell me where i went wrong?
Thanks in advance.
 
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  • #2
Do you expect the helium cylinder to be completely empty after all the balloons that can be inflated are inflated?
 
  • #3
gneill said:
Do you expect the helium cylinder to be completely empty after all the balloons that can be inflated are inflated?
If the volume of helium in the balloon is 0.15m3 at that pressure, then why not? We use all the 0.15m3 because 0.15 is divisible by 0.030 without any remainders...
 
  • #4
UnknownGuy said:
If the volume of helium in the balloon is 0.15m3 at that pressure, then why not? We use all the 0.15m3 because 0.15 is divisible by 0.030 without any remainders...
So the final pressure in the cylinder will be zero? A perfect vacuum? How does the last of the gas get moved to balloons where the pressure will be nonzero?
 
  • #5
gneill said:
So the final pressure in the cylinder will be zero? A perfect vacuum? How does the last of the gas get moved to balloons where the pressure will be nonzero?
Ah, now I understand.. Thank you very much!:biggrin:
 
  • #6
:smile:
 
  • #7
gneill said:
Do you expect the helium cylinder to be completely empty after all the balloons that can be inflated are inflated?
Yes just like in electricity questions we ignore resistance
 
  • Skeptical
Likes berkeman
  • #8
Pegasus said:
Yes just like in electricity questions we ignore resistance
Please note that this thread is more than 6 years old. Also note that in electricity questions we don't usually ignore resistance, especially when there is current flowing.
 
  • #9
Pegasus said:
Yes just like in electricity questions we ignore resistance
Your analogy does not work. The balloon filling problem is more akin to charging capacitors from a given capacitor.
And the correct answer to @gneill's question is no. Or were you being sarcastic?
 

1. How does pressure affect the number of balloons that can be inflated?

The amount of pressure applied to a balloon determines how much air it can hold. The higher the pressure, the more air can be pumped into the balloon, allowing it to inflate to a larger size.

2. Is there a limit to how many balloons can be inflated with a given amount of pressure?

Yes, there is a limit to how many balloons can be inflated with a given amount of pressure. This limit depends on the size and strength of the balloons, as well as the amount of pressure being applied.

3. Can different types of gas affect the number of balloons that can be inflated?

Yes, different types of gas can affect the number of balloons that can be inflated. For example, helium gas is less dense than air, so it can fill more balloons than air can at the same pressure.

4. How does temperature impact the number of balloons that can be inflated?

Temperature plays a role in the number of balloons that can be inflated. As the temperature increases, the air inside the balloon expands, allowing it to hold more air and inflate to a larger size. However, extreme temperatures can also cause balloons to burst.

5. Is there a standard amount of pressure used for inflating balloons?

There is no standard amount of pressure for inflating balloons. The amount of pressure needed depends on the size and strength of the balloons, as well as the desired size of the inflated balloon. It is important to follow the instructions provided with the balloons to ensure they are inflated safely and to their desired size.

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