Homework chapter 8 #3 part a

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Nicholas Fierro 1E
Posts: 9
Joined: Wed Nov 18, 2015 3:00 am

Homework chapter 8 #3 part a

Postby Nicholas Fierro 1E » Sat Jan 21, 2017 9:12 pm

Air in a bicycle pump is compressed by pushing in the handle. If the inner diameter of the pump is 3.0 cm and the pump is depressed 20cm with a pressure of 2.00 atm (a) how much work is done in the compression?
I am not quite sure how to approach this problem because the height of the bicycle pump isn't given therefore I am not sure how to go about finding the total volume of the bicycle pump and cannot find the change in volume as a result. Any suggestions? Thank you!

Selena_Wong_1I
Posts: 13
Joined: Wed Sep 21, 2016 2:56 pm

Re: Homework chapter 8 #3 part a

Postby Selena_Wong_1I » Sat Jan 21, 2017 9:29 pm

The volume of an object is length * width * height. In this particular case, we are trying to find the volume of a cylinder shaped object. The length * width portion of the volume is the cross section area of the cylinder, which is just the area of a circle (pir^2). We are given the diameter (3 cm), so to find the radius, we divide 3 cm by half to get 1.5 cm. The height portion of the volume is the distance traveled (-20 cm). So to find the volume (length*width*height), we multiple pi*(1.5 cm)^2*(-20 cm) to get -141.37 cm^3. We then use the conversion factor (1L=1000cm^3) to change the units to L.


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