Heat in the Environment: Unit Review

Any four: all matter is made of tiny particles; particles are always moving; there are spaces between particles; particles attract each other; heating makes particles move faster; each pure substance has its own kind of particle.

Close together but not in a pattern; they slide past each other.

Smell particles escape into the air and, because particles are always moving, they spread out through the spaces between air particles (diffusion) until they reach your nose.

Temperature is the average speed (energy of motion) of the particles. Thermal energy is the total energy of all the particles, so it also depends on how much matter there is.

The bathtub, because it has far more particles.

From the hot cocoa to the cold milk, until they reach the same temperature.

They vibrate faster and harder in their places.

(a) nuclear (fusion), (b) electrical, (c) mechanical (friction), (d) chemical (combustion).

Bacteria and fungi break down the plant material in chemical reactions that release heat.

Any one: a laptop or phone warming up; a car engine getting hot; old-style light bulbs.

Its particles move faster and farther apart. They do not get bigger.

So the bridge can expand and contract with temperature changes without cracking or buckling.

It expands (by about 9%). Effects: ice floats; pipes can burst; potholes form; rocks crack (frost wedging).

About 218 mL. 9% of 200 = 18; 200 + 18 = 218.

The energy going in is used to overcome the attraction between particles and break them out of their fixed places, not to make them move faster.

Liquid → gas (for example, water boiling into water vapour).

As sweat evaporates, the fastest particles leave and carry thermal energy away from your skin.

Heat transfer by direct contact, as particles bump into their neighbours and pass on energy.

Metal is a good conductor, so it carries heat away from your hand faster.

Any one: Earth's inner heat moving through rock; warm ground heating the air touching it; snow insulating the soil; permafrost thawing; animals losing heat to cold air or water.

The particles must be able to move from place to place. In solids they are held in place.

Land heats faster. Warm air over the land rises, and cooler, denser air from over the lake flows in to replace it.

Any two: wind, lake breezes, thunderstorms, thermals for soaring birds, lake turnover, ocean currents, mantle convection.

It does not need particles, so it can travel through empty space.

The dark parking lot. Fresh snow reflects most sunlight.

The darker ocean water that is exposed absorbs more sunlight than ice, so it warms and melts more ice.

It keeps giving off infrared radiation to space, with no incoming sunlight to replace it.

They absorb infrared radiation from Earth's surface and send some of it back down, keeping the surface warmer.

Without it Earth's average temperature would be about −18 °C, too cold for most life.

Extra warming caused by greenhouse gases added by human activities.

CO₂: burning gasoline, diesel, natural gas or oil; cutting forests; making cement. Methane: landfills, livestock, natural gas leaks.

11.5 kg. 5 × 2.3 = 11.5.

Any two: better transit and bike lanes; electric buses; capturing landfill methane; low-emission electricity; protecting forests and wetlands; building codes for efficient homes.

A sealed layer of air or argon gas between the panes slows conduction and convection.

Social: lower heating bills or a more comfortable home. Environmental: less fuel burned, so fewer greenhouse gases.

The lower entrance lets cold, dense air settle there instead of flowing into the living space; the raised sleeping platform is where warm air collects.

Benefit: renewable, very low emissions, reliable. Drawback: dams flood land and change rivers and fish habitat, and some have flooded First Nations lands.

(a) social, (b) economic, (c) environmental.

Diesel is expensive to bring in and causes pollution and greenhouse gases. Connecting to the grid or adding solar, wind or hydro can lower costs and emissions.