I need help with understanding were to start

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Dr_fox

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Feb 3, 2021
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The pressure in a cylinder is given by
P(t)=101+k/t
Assume that t ≥ 1 and k is constant.
At time t = 7.5 minutes the pressure is changing at −1.35 kPa/min. Find k.
Your answer should be accurate to 1 decimal place and must include units.
If you are not sure how to enter unusual combinations of units
 
Dr_fox said:
The pressure in a cylinder is given by
P(t)=101+k/t
Assume that t ≥ 1 and k is constant.
At time t = 7.5 minutes the pressure is changing at −1.35 kPa/min. Find k.
Your answer should be accurate to 1 decimal place and must include units.
If you are not sure how to enter unusual combinations of units
Click to expand...
Is your function:

P(t) = 101 + k/t..................................................This is what you wrote.

or

P(t) = \(\displaystyle \frac{101 + k}{t} \)..................................................This is what you should have written: P(t) = (101 + k)/t

What do you understand from the statement (mathematically):

........the pressure is changing at −1.35 kPa/min​

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:


Please share your work/thoughts about this problem.[/tex]
 
Dr_fox said:
I tried the d/dt(100+(k/t))=-(k/x2) then use time and -1.35 kPa/min to find k and also tried to use https://www.desmos.com/ to graph it to help find k thous both did not work
Click to expand...
Please pay attention to what you are doing!

How did you get d/dt (100 + k/t) = - k/x^2 ..................................where did 'x' come from? I think you meant: d/dt (100 + k/t) = - k/t^2

You say: "...I tried the d/dt(100+(k/t))=-(k/x2) then use time and -1.35 kPa/min to find k"

Please share your "numerical work" of calculating "k".
 
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