HOMEWORK!

OBJECTIVE ONE

The three common temperature scales are Fahrenheit, Celsius, and Kelvin.

Thermal energy is related to temperature and heat because the measure of thermal energy depends on the temperature of an object.

Having a high specific heat means that it takes a lot of thermal energy to heat up one km² of a substance by one kelvin.  For example, water has a higher specific heat than sand and iron.

An ice cube melts in your hand because nature is trying to obtain an equilibrium.  Some of the thermal energy from your hand is being transferred to the ice cube.

Some materials get hotter more quickly than other because they have a low specific heat.  It takes a lot less energy to heat them up than some things.

OBJECTIVE TWO

Thermometers measure temperature  by using either mercury or colored alcohol.  Mercury or colored alcohols expands when heated.  As the temperature rises, the mercury/colored alcohol goes higher.  When cooled, mercury/colored alcohol becomes smaller. (http://www.energyquest.ca.gov/how_it_works/thermometer.html)

The three temperature scales, Fahrenheit, Celsius, and Kelvin, are similar because they all measure temperature.  However they are different.  Fahrenheit has the freezing point of 32 degrees and the boiling point of 212 degrees.  It is also used by the US and many other amazing, prosperous countries. (Please take this time to note any and all sarcasm) Celsius has a freezing of 0 degrees and a boiling point of 100 degrees.  It is used by any country in the world that is not called Jamaica, Belize, Palau, USA, or Liberia.  Therefore it is used by Canada.  Kelvin is used to measure massive amounts of heat or very cold temperatures.   The freezing point is 253 degrees and the boiling point is 353 degrees.

5 degrees Celsius is the same as 41 degrees Fahrenheit.

Venus can get up to 460 degrees Celsius.

It takes 209,000 J to heat 5 kilograms of water by 10 K.

OBJECTIVE THREE

The three forms of heat transfer are conduction, convection, and radiation.  Conduction is heat being transferred when matter not moving.  Convection is heat being transferred through waves in a fluid, and radiation is heat being transferred through electromagnetic rays.

Heat always moves from hot to cold.

Conductors allow heat to transfer easily whilst insulators prohibit the transfer of heat.

I think copper pipe would be a good conductor.  It is made out of a metal, and metals are usually conductors.  It is also cold to the touch.  Copper pipes are used for plumbing and air conditioning so they must be good about heat transfer.

If I was camping on a mountain and suddenly got cold, I would shear a sheep and wrap its warm, soft wool around me.  Wool is a good insulator.  This is an example of conduction.  I would then light a fire with the remains of a chicken, sacrificed on the night of a full moon (convection).  If I was still cold, (though this would be very unlikely due to the warmth of chicken fire), I would wrap myself in paper (also a good insulator).  Of course, I would accidentally use the homework I was supposed to be finishing, so if I ever fail to turn in my homework, I hope you understand why.

OBJECTIVE FOUR

Change in thermal energy causes a change in state of matter.

As thermal energy increases, matter melts.

Temperature stays the same as matter’s state changes because the thermal energy is being used to change the state whereas when state doesn’t change, the thermal energy merely raises the temperature.

Solids melt when put up to enough thermal energy.

You should poke holes into a potato before baking it because, if you don’t, the water will turn into steam that will try to escape.  When the steam’s plans to escape are thwarted, it will get angry and kill the potato through an epic explosion.

OBJECTIVE FIVE

Heat engines use thermal energy to do many magical things.  The thermal energy powers the engine, hence the name.

In external combustion engines, the combustion happens from an external source and heats up the inside fluid.  In an internal combustion engines, the expansion of a gas due to combustion powers part of the engine (causes it to move).

“In mobile equipment, internal combustion is advantageous since it can provide high power-to-weight ratios together with excellent fuel energy density.” (http://en.wikipedia.org/wiki/Internal_combustion_engine)

The state changes in the refrigerant of a refrigerator are gas to liquid or vice versa.

If the compressor in a refrigerator stopped working, the refrigerator wouldn’t get cold enough because the compressor wouldn’t make the air a high-pressure vapor.