Fluids Review Flashcards
Atmospheric pressure in pascals, n/m2, psi, mmhg, inHg
101,000 n/ m2 and Pascals
14.7psi
760 mmHg
30inHg
3 ways to change pressure of container
Heat up the gas so it has more kinetic energy and therefore more collisions.
Make the container’s volume less so there are more collisions.
Add more gas so there are more collisions.
- How does a barometer work?
The atmosphere’s pressure pushes down on the mercury, causing it to push up in the tube.
- How does a drinking straw work?
When you breathe in the air in the straw, it decreases the air pressure inside of it. Pressure moves from high to low, so the higher air pressure around the straw will push the liquid into the straw.
Bernoulli’s Principle
Faster fluid creates lower pressure, slower fluid creates higher pressure
b. This barometer is taken down into a Death Valley below sea level. What will happen to the mercury in the tube? Explain.
The mercury in the tube will rise further in because there is higher pressure around it and it will be moving in, pushing it up.
c. This barometer is taken to Denver above sea level. What will happen to the mercury in the tube? Explain.
The mercury will descend out of the tube because there is lower pressure around it, and it moves from high to low.
Explain in fizix terms why high heel shoes get uncomfortable while wearing them
The weight of your body is distributed on a small space of area. Because of F/A, your weight F divided by a small A means a higher pressure than your weight F divided by a bigger A (normal shoes).
Missing force sink rise or float problem
- Which way would a piece of paper on the dash board of a car tend to go if the windows are rolled down while the car is moving down the freeway? Why?
The paper goes out the window because the car has higher pressure than the outside, which means the outside has faster fluid. And air moves from high to low, so the paper moves out.
- Why does your shower curtain have a tendency to push inward toward you when you’re in the shower? Explain.
Turning the shower on moves air out of the way and creates faster moving air, so the air pressure there is dropping. The higher pressure on the other side is trying to move in.
- Be able to explain each of the demos from the Bernoulli demo day and the moving fluids lab.
Ball and funnel:
Coin:
Two cans:
Paper strip:
Atomizer:
Leaf blower:
Toilet paper:
Trash bag:
Ball and funnel: The top of the ball has the fastest traveling fluid, so the bottom of the ball has the highest pressure, keeping it aloft.
Coin: Fluid is traveling the fastest on the dime’s top surface, so the bottom has higher pressure. As that higher pressure tries to move up, it flipped the coin.
Two cans: Fluid is traveling fast in between the cans, and the higher pressure on the outside of the cans is moving in, pushing the two together.
Paper strip: Fluid is traveling fast on the top of the paper, on the bottom side there is higher pressure and it’s trying to go to the low-pressure environment, pushing up and straightening out the paper.
Atomizer: Blowing fast air across the opening, creating low pressure area that pushes the contents up (high to low)
Leaf blower: Faster air is on the top of the ball and there is higher pressure on the bottom, so it’s being kept aloft.
Toilet paper: Faster air on topside, higher pressure on bottom, pushing to get to the low-pressure area so the paper is scrolled out.
Trash bag: Blowing fast air into the hole, so it has lower pressure, now the outer high pressure moves in to fill it.
p = m/v problem (v is not cubed yet)
archmiedes principle
An object submerged in a fluid is buoyanced (pushed) up by a force equal to the weight of the fluid displaced.
