Force Question

Hi,

Yes the maths are correct but the unit is 1200 pounds force not kn.

Also it is the theoretical thrust the cylinder develops at the end of it's stroke, not the force developed whilst it is moving.

It also doesn't take into account frictional losses.

Best regards,

John

Mashed up brain when dancing with the beers?

Just do the following:

Convert units before calculation, then apply formula.

Alternativly calculate first and get what you get and then convert the units.

But then: where is Kilo Newton coming from????

Looks like I need a beer too!

Direction clear?

Probably easier to do the imperial calculation(remembering what the units are) and then convert the final answer to metric. Less chance of errors that way. Besides, it is still common to work in both systems so a knowledge of both isn't going to be so bad, is it??

One needs to know the formula for either one. Sometimes imperial units have multipliers in there to account for their specific relationships.

It would be useful to understand the basic concept of Pressure, Area and Force first before attempting this calculation. Being able to multiply units is also essential in this exercise.

He is not coming back, probably too much beer . . .

Inches or square inches?

What are imperial SI units? It's either one or the other, and yours are imperial! Not difficult to convert, but you can't mix them up. Also you presumably mean 10 square inches.

Or 10 inches diameter/radius on the piston!

Who knows?!

Could you copy the problem directly from the test and not paraphrase, please?

http://en.wikipedia.org/wiki/Dimensional_analysis Factor Label Method, yes, that was a very important concept that you and many of your fellow students glossed over. You'll be amazed at how helpful it is to have the intermediate units cancel out and yield the correct final unit. It is very helpful when going back an forth between metric (SI) {good} and English (Imperial) {bahh humbug} units. I don't know what an imperial SI unit is but if you figure it out then the Factor Label Method will work with it.

I like Lyn's answer.

like others have noted: pick your unit system first, either one or the other and if you are saying your piston has an area of 10 inches, it should be square inches in which case your piston is only 3.568" in diameter since:

area = pi(r^2)

Good Luck on the test.

Dear Mr.Danceswitheers,

Very simple. Calculate the area for 10 Inches, it will be (Pi/4) x 10^2 = 78.5 Sq.In

Total Load = Area x Pressure = 78.5 x 120 = 9420 Lbs. or Pounds. This load can be converted to newtons.

DHAYANANDHAN.S

Free answers instead of free education.