PHYS Ch. 4 Fluids

Question 1

What is the equation for density?

Answer 1

p = m/v
p (rho) = density, m = mass, v = volume

Question 2

What is the density of water?

Answer 2

1 g/cm^3 = 1000 kg/m^3

Question 3

What is the equation for specific gravity?

Answer 3

SG = p/1g/cm^3

Question 3

What is the equation for pressure?

Answer 3

P = F/A
P = pressure, F = force, A = area

Question 4

What does 1 Pa equal in Newtons?

Answer 4

1 Pa = 1 N/m^2

Question 5

What are the units of pressure?

Answer 5

pascals (Pa), millimeters of mercury (mmHg), torr, and atmosphere (atm)

Question 6

What are the units of density?

Answer 6

kg/m^3
g/mL
g/cm^3

Question 6

What are the conversions b/w Pa, mmHg, torr, and atm?

Answer 6

1.013 x 10^5 Pa = 760 mmHg = 760 torr = 1 atm

Question 7

What is absolute/hydrostatic pressure?

Answer 7

the total pressure that is exerted on an object that is submerged in a fluid

Question 8

What is gauge pressure?

Answer 8

the difference between the absolute and atmospheric pressure

Question 9

What is the equation of absolute/hydrostatic pressure?

Answer 9

P = Po + pgz
Po = incident/ambient pressure (pressure at the surface)
p = density of the fluid
g = acceleration due to gravity
z = depth of the object

Question 10

What is the equation for Pascal’s principle of a hydraulic system?

Answer 10

P = F1/A1 = F2/A2
F2 = F1 [A2/A1] or F2 = m*g [A2/A1}^2
A = cross-sectional area, F = force, P = pressure
m = mass in kg, g = gravity (10m/s^2)

Question 11

What is the equation for Pascal’s principle of volume in a hydraulic system?

Answer 11

V = A1d1 = A2d2
d = d1 [A2/A1]
A = cross-sectional area, d = distance

Question 12

What happens to force as area increases in a hydraulic system/piston?

Answer 12

the larger the area, the larger the force exerted

Question 13

What is Archimedes’s principle?

Answer 13

it states that a body wholly or partially immersed in a fluid will be buoyed upward by a force equal to the weight of the fluid that it displaces

Question 14

When will an object float or sink?

Answer 14

an object will float if its average density is less than the average density of the fluid it is immersed in, and vice versa

Question 15

What is buoyant force?

Answer 15

buoyant force is the force of a liquid. if 2 objects are placed in a fluid of the same volume, both objects will experience the same magnitude of buoyant force even if the masses of the objects are different

Question 16

What is the correlation between specific gravity and floating or sinking?

Answer 16

an object with a specific gravity less than or equal to 1 will float in water and vice versa

Question 17

What is the density of seawater?

Answer 17

1025 kg/m^3

Question 18

What is the density of an ice cube in water?

Answer 18

0.92 g/cm^3 = 92 specific gravity, which means 92% of its volume is submerged in water and 8% is sitting above the surface

Question 19

What is the equation for buoyancy?

Answer 19

Fb = mg = pVg
p = density of fluid, v = volume of fluid, g = gravity
m = weight

Question 20

What is cohesion?

Answer 20

the attractive force that a molecule of liquid feels towards other molecules of the SAME liquid

Question 21

What is adhesion?

Answer 21

the attractive force that a molecule of liquid feels towards the molecule of another substance

Question 22

What is the difference between a meniscus and a convex meniscus formation?

Answer 22

a meniscus (curve) forms when the adhesive forces are greater than the cohesive forces. a convex meniscus occurs when the cohesive forces are greater than the adhesive forces

Question 22

What is the only metal that is liquid at room temperature?

Answer 22

Mercury

Question 23

What is the temperature at absolute zero?

Answer 23

0 celsius = -273 K