# Ch 15 slides

```Phases of matter
Higher order
solid
Lower order
liquid
gas
T
Mesophases
some positional
and orientational
order
solid
Thermotropic
Liquid crystals
Smectic C
Smectic A
orientational
order
Nematic
liquid
T
Straw Pressure
If you put your finger on top of a drinking straw
submerged in water, you can hold the water in the straw
when you draw it out of the water.
•
•
Draw a force diagram to show why this happens
If the water in the straw is 10cm high, what it the
pressure at the top and the bottom of the straw?
Hydraulics
Consider a hydraulic lift, such as the one that lifts your car
at the repair shop. The system is in static equilibrium if
Lifting a car
The hydraulic lift at a car repair shop is filled with oil. The car
rests on a 25-cm-diameter piston. To lift the car, a force is
applied to push down on a 6 cm diameter piston.
• What force will support a 1300 kg car level with the small
piston?
• If you lift the car up by 2m, by how much do you need to push
the small piston?