# Column cross-sectional area (cm2)

1. Sep 23, 2004

### mountain

hello guys!

i have a column with a shape of a cylinder. the radius is 2cm and the heigh is 5cm. i have to calculate the cross-sectional area of the column. i wonder what is the formula and how is the calculation? it has been a long time since i last had my math lectures, so i really hope for some help!

thanks alot!

2. Sep 23, 2004

### Sirus

Well, draw a picture of a cylinder and visualize/draw the cross-sec. area. What is the shape of this area? How do you find the area of figures of that shape?

3. Sep 23, 2004

### mountain

hi sirus!

my problem is that i don't know what it means with "cross-sectional area"

if the column has a shape like a circular cylinder with a radius of 2cm and the length/high of the column is 5cm.

how would you find the cross-sectional area?

hope for ideas!

4. Sep 23, 2004

### Tide

Imagine the cylinder standing one of its ends and make a horizontal cut through it. What shape do each of the NEW ends have? That is the cross section.

5. Sep 23, 2004

### mountain

hi Tide!

cross-section is that, but what about cross-sectional area of the column? is that the areal of it?

6. Sep 23, 2004

### recon

I don't think mountain will be coming up with the correct answer anytime soon. So I'll just come straight out with the answer. The cross-section of a cylinder is in the shape of a -----e. No matter where you horizontally cut a standing cylinder, the ends of the cut pieces you make will be in a shape of a -----e.

Ooops, not quite as un-cryptic as I'd hoped. Another hint: The area of the cross section has something to do with the number 3.14159265.....

7. Sep 23, 2004

### Tide

Mountain,

Since Recon gave such a cryptic message -- prepare to slap yourself on the forehead --- the cross secion is a CIRCLE! :-)

I'm sure you can handle it from there.

8. Sep 23, 2004

### Sirus

Mountain, try to read up on this in your textbook a little. Once you grasp it, cross-sectional area will be easy for you.

9. Sep 24, 2004

### mountain

Geeze guys! this is emergency and you guys are playing with my time :yuck:
anyway i have got the answer from some more helpful people :tongue2: it is A= pi*r^2

10. Sep 24, 2004

### Sirus

Sorry if you were pressed for time, but we don't give answers on this forum. We help people understand concepts and approaches to questions so they can find the answers themselves. You don't learn anything if someone gives you the answer to a question.

11. Aug 14, 2009

### lil_syed_97

alright it is easy this is how........Take the raduis(power of 2) after converting it to the power form then you multiply it by 3.14=Pie....The answer is your cross sectional area.

Example.

Suppose a diameter is 40 cm.I convert it to the radius that is 20 cm. Then i convert again the 20 cm in the power 2 format. That becomes 400 cm. After that you multiply the 400 by 3.14(Pie Calculation) that gives you 1256 cm..So 1256cm is your cross sectional area.

12. Aug 14, 2009