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March 29, 2024, 11:44:01 am

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fredrick

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Question
« on: April 27, 2008, 06:56:05 pm »
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I dont know where to start on this one, any help is appreciated.

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iamdan08

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Re: Question
« Reply #1 on: April 27, 2008, 07:44:58 pm »
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This question is from the 2005 exam. There is information prior to this question which states the mass of the rocket is 0.2 kg.

Knowing this:



(acceleration due to gravity)



 
Subtract the retarding force:










« Last Edit: April 27, 2008, 07:50:28 pm by iamdan08 »
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Mao

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Re: Question
« Reply #2 on: April 27, 2008, 08:51:16 pm »
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This question is from the 2005 exam. There is information prior to this question which states the mass of the rocket is 0.2 kg.

didnt checkpoints include this?


easier method:

net retardation:





net acceleration = g - retardation

« Last Edit: April 27, 2008, 08:53:45 pm by Mao »
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fredrick

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Re: Question
« Reply #3 on: April 27, 2008, 08:53:56 pm »
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Thanks! the checkpoints 2008 doesn't state the mass!
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iamdan08

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Re: Question
« Reply #4 on: April 27, 2008, 08:54:07 pm »
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I just checked my checkpoints and no it doesn't. That is really weird and stupid! No wonder he didn't know where to start! lol
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Mao

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Re: Question
« Reply #5 on: April 27, 2008, 08:54:41 pm »
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they even fail at copy-pasting....

I wonder what they'll do next!
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fredrick

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Re: Question
« Reply #6 on: April 27, 2008, 08:56:39 pm »
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they even fail at copy-pasting....

I wonder what they'll do next!

L0L
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ed_saifa

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Re: Question
« Reply #7 on: April 27, 2008, 08:59:40 pm »
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Told you physics was ambiguous. Amazing how so many people in my class managed to do it without this information..
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Mao

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Re: Question
« Reply #8 on: April 27, 2008, 09:13:26 pm »
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Told you physics was ambiguous. Amazing how so many people in my class managed to do it without this information..
what!
what was the answer?
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fredrick

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Re: Question
« Reply #9 on: April 27, 2008, 09:15:13 pm »
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Maybe its assumed knowledge that test rockets have a mass of 0.2 kg
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dcc

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Re: Question
« Reply #10 on: April 27, 2008, 09:21:33 pm »
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As the curve of retarding force levels out at 2N, it is a safe assumption to make that this is the point when , which means that you can make your retarding force equal to the weight force, which gives the 0.2kg mass as required.  

Parachutes cannot provide an acceleration upwards for a long amount of time, so that flattening out suggest that terminal velocity has been reached.

One would only make assumptions like these if you didn't have the mass defined for you, because its risky business.

p.s. since the rocket would presumably be a small object, there is no worry that the parachute has just reached its 'maximum retardation force', but rather that it cannot retard any more

iamdan08

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Re: Question
« Reply #11 on: April 27, 2008, 10:36:01 pm »
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As the curve of retarding force levels out at 2N, it is a safe assumption to make that this is the point when , which means that you can make your retarding force equal to the weight force, which gives the 0.2kg mass as required. 

Hmmm. That is a good point.
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Captain

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Re: Question
« Reply #12 on: April 28, 2008, 06:10:25 pm »
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As the curve of retarding force levels out at 2N, it is a safe assumption to make that this is the point when , which means that you can make your retarding force equal to the weight force, which gives the 0.2kg mass as required.  

Parachutes cannot provide an acceleration upwards for a long amount of time, so that flattening out suggest that terminal velocity has been reached.

One would only make assumptions like these if you didn't have the mass defined for you, because its risky business.

p.s. since the rocket would presumably be a small object, there is no worry that the parachute has just reached its 'maximum retardation force', but rather that it cannot retard any more

That's how I did it. :)

Btw fredrick, by this stage of the year, you should be way further ahead in your checkpoints.  Spend one weekend to catch up :P