Fluids

Question 1

Density

Answer 1

=ρ = m/V

- Units: kg/m^3 or g/mL or g/cm^3

Question 2

Weight (Given density) Formula (Buoyancy)

Answer 2

=F(gravity)= ρVg

Question 3

Specific Gravity

Answer 3

= SG = ρ /1 g/cm^3

Question 4

Pressure

Answer 4

• Ratio of force (normal) per unit area
  = P = F/A
• Unit= pascal (Pa)
  = 1.013x10^5 Pa = 760 mmHg = 760 torr = 1 atm

Question 5

Absolute (Hydrostatic) Pressure

Answer 5

= P= P(o) + ρgz

• P is the absolute pressure
• P(o) is the incident or ambient pressure (at surface)
• ρ is the density of the fluid
• g is the acceleration due to gravity
• z is the depth of the object

Question 6

Gauge Pressure

Answer 6

= P (gauge) = P-P(atm)= (P(o) + ρgz) - P(atm)

Question 7

Pascal’s Principle

Answer 7

=P= F(1)/A(1)=F(2)/A(2)

= F(2)=F(1) x (A(2)/A(1))

-Volume of fluid displaced by piston 1 is equal to the volume of fluid displaced at piston 2
= V =A(1)d(1)=A(2)d(2)
=d(2)= d(1) x (A(1)/A(2)

• The larger the area, the larger the force exerted through a smaller distance

Question 8

Work Equation for Hydraulic Lift

Answer 8

=W= PΔV=F(1)/A(1) x (A(1)d(1)) =F(2)/A(2) x(A(2)d(2))

=F(1)d(1)= F(2)d(2)