Fluids: Unit Review

Viscosity is a fluid's resistance to flow. Warming a liquid lowers its viscosity, because faster particles slide past each other more easily.

450 ÷ 90 = 5 mL/s.

Dish soap (lower flow rate).

Any four: pressure difference, viscosity, temperature, pipe diameter, pipe length, bends, roughness or obstructions.

It is an obstruction that narrows the path, so less water gets through each second.

Greater height gives a bigger pressure difference, so water flows out of taps with more push.

30 ÷ 12 = 2.5 g/cm³.

V = 265 − 250 = 15 mL. D = 45 ÷ 15 = 3 g/cm³.

About 2 kg (2000 mL × 1 g/mL = 2000 g).

19.3 × 2 = 38.6 g.

Gas particles are far apart, so the same mass takes up a much bigger volume: lower density.

Freezing water forms an open particle pattern, so ice has more volume for its mass and is less dense than liquid water.

Heated air expands, so it is less dense than the cooler air around it, which sinks and pushes it up.

Water: floats (0.85 < 1.00). Oil: floats (0.85 < 0.92).

0.6 ÷ 1.00 = 60%.

Its average density, including all the air inside the hull, is less than water's.

Gas particles have large spaces between them; liquid particles are already close together.

Compressed gas (any): tires, scuba tanks, air brakes, nail guns. Incompressible liquid (any): car brakes, hydraulic excavators, car lifts.

Air compresses, so part of the pedal push is wasted, and the car may take longer to stop.

It increases. The particles move faster and hit the walls harder and more often.

It decreases: the cooled particles push less on the balloon.

Heated water expands and can't be compressed, so pressure in the closed tank could rise until it bursts. The valve lets water out.

90 ÷ 15 = 6 N/cm².

Pressure applied to a fluid in a closed container is passed on equally to every part of the fluid and its walls.

P = 12 ÷ 3 = 4 N/cm². F₂ = 4 × 45 = 180 N.

Volume = 3 × 30 = 90 cm³. Distance = 90 ÷ 45 = 2 cm.

Hydraulic systems use a liquid (nearly incompressible); pneumatic systems use a gas, usually compressed air (compressible).

Nail gun: pneumatic. Excavator arm: hydraulic.

Air leaks are clean; oil leaks from hydraulics could contaminate food.

Both create a pressure difference to move a fluid, and both use one-way valves to stop backflow.

By opening and closing their stomata.

It stays on. 12 cm is not below 10 cm, so the OFF branch doesn't run.

Environmental, social and economic.

Positive (any): little greenhouse gas while running; reliable power; long life. Negative (any): floods land, including First Nations lands; blocks fish; mercury in fish; high building cost.

Any one: the Inuit qajaq (buoyant, stable kayak), the Inuit avataq (air-filled sealskin float), or the birchbark canoe (light, floats high, carried over portages).

Any two of density, viscosity, temperature, the water's flow. For example: most oil is less dense than water, so it floats and spreads.

Each method has limits: booms fail in waves, skimmers are slow, dispersants leave oil in the water, sunken oil is hard to reach, and some oil sticks to shores and wildlife.

Any one: harm to harvesting and food sovereignty; harm to culture and ceremony; health effects; remote communities wait longer for help; effects on their rights to lands and waters.