Easy pressure and fluid problemsi swear

  • Thread starter Thread starter Dantes
  • Start date Start date
  • Tags Tags
    Fluid Pressure
AI Thread Summary
The discussion focuses on solving pressure and fluid problems involving a woman on high heels, a submerged Ping-Pong ball, and a floating object in two liquids. For the pressure exerted by the woman, the correct calculation reveals a factor of 10 error, leading to a pressure of 14,480.35 N/m². The buoyant force for the Ping-Pong ball requires calculating the mass of displaced water based on its volume, which is approximately 3 cm³. The third problem regarding the density of a floating object lacks sufficient information about the second liquid's density, complicating the solution. Participants express a desire to learn and confirm their understanding of these concepts.
Dantes
Messages
18
Reaction score
0
easy pressure and fluid problems..i swear :)

Got some (what I think) are easy pressure and fluid problems.

A 23.5 kg woman balances on one heel of a pair of high-heeled shoes.The acceleration of gravity is 9.8 m/s^2 :If the heel is circular with radius 0.225 cm,
what pressure does she exert on the floor? Answer in units of N/m^2.


On this one I been doing (23.5*9.8)/((.225 x 10^-2)^2*pi) and i get 1448.03 without the conversion to meters i get 14480348.99 which seems a little high. But 1448.03 is wrong..what am i doing wrong.

A Ping-Pong ball has a diameter of 1.79 cm and average density of 0.0377 g/cm^3.The acceleration of gravity is 9.8 m/s^2 :What force would be required to hold it completely submerged under water? Answerin units of N.

On this one I got the volume of the ping ball by 4/3*pi*(1.79/2)^3 which came out to be 3.003 cm^3 and when applying the bouyant force equation of B = p sub f * volume of the object * gravity I get 29429.4 N which comes out to be wrong. Do i need to take that number and multiply it by the area for the force? The numbers seem really high.

A homogeneous solid object floats on water with 69 percent of its volume below the surface. The same object when placed in a second liquid floats on that liquid with 66 percent of its volume below the surface. Find the density of the object. Answer in units of kg/m^3. Also what is the specific gravity of the liquid?

On this one i have no idea where to start since it doesn't give me any densities of the liquids other then water which i can only assume to be fresh water with 1.0 X 10^3.

Any help on these would be great sort of want to learn this stuff and not be doubt with the answers I get are right or not.
 
Physics news on Phys.org
Q1: you're out by a factor of 10. Ans is 14,480.35 N/m²

Q2: the density of water is 1 gm/cc. The volume of the displaced water is 3 cm^3. So the mass of the displaced water is about 3 gm. Convert that to kg and multiply by g to get the bouyant force

Q3: sorry, no time to answer.
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanged mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top