pressure

[Guest stackattack]

hey guys i'm in Ap physics B and was wondering if anyone could help me out with this problem:

Estimate the pressure exerted on a floor by the following.

(a) a

53

kg model standing momentarily on a single spiked heel (area =

0.06

cm2)

(

a

1545

kg elephant standing on one foot (area =

800

cm2)

[Guest moe.ron]

Well, the equation you would use here is P = F/A (Pressure = Force/Area)

This was like a day topic in Cermak's class - so im not sure what unit you want it in. If it is N/(cm^2) all you would have to do in this case is find the weight (W=mg) so in case a the weight is 530N (assuming g=10 m/s^2). That is the force. Then just plug that into P = F/A. The force is 530N, the area is .06 cm^2. 530/.06 = 8833 N/cm^2. If the answer you want is not in cm^2 (most of the time physics is in meters but im not sure in this case...) you would want to move the decimal place over accordingly, before you divide.

[Guest moe.ron]

oh and i dont know how complicated your pressure problems get. but F in this case is the NORMAL force. On a flat plane the Weight is equal to the Normal Force, but if you were on a slant, you would have to account for the angle by using the normal force instead.

[Guest moe.ron]

And sorry to keep adding to this... but upon further investigation - you might want to be in Pascals (does that sound farmilar lol?). That is in N/m^2 so you will need to figure out how many m^2 you have from cm^2. There are 100 cm in a m, so 10,000 cm^2 in a m^2 (100x100=10000). Divide your area given by 10,000 to find how many m^2 you have instead and then plug that number into P=F/A as the A instead of in cm^2 and you will have your answer in pascals.

[Guest stackattack]

thank you so much! i never would have figured that out haha

[Guest moe.ron]

haha no problem, your best bet is to check the regents physics reference table for the equations. If you know P=F/A then you have figured out the hardest part of the problem.