Chapter 9 science

Distinguish between a joule and a calorie.

1 calorie= 4.18 joules.

By how much does the pressure of a gas in a rigid vessel decrease when the temperature is decreased by 1 degrees celsius?

1/273.

What is the temperature of melting ice on the kelvin scale? Of boiling water at atmospheric pressure?

273 K. 373 K.

At what temperature do the combined effects of contraction and expansion produce the smallest volume for water?

4 degrees.

Temperature

A measure of the hotness of an object, related to the average kinetic energy per molecule in the object, measure in degrees Celsius, degrees Fahrenheit, or kelvins.

First law of thermodynamics

A restatement of the law of energy conservation, usually as it applies to the thermal systems: Whenever heat flows into or out of a system, the gain or loss of thermal energy equals the amount of heat transferred.

Calorie

A unit of thermal energy or heat. One calorie is the thermal energy required to raise the temperature of one gram of water one Celsius degree (1 cal= 4.18 J). One Calorie (with a capital C) is equal to 1000 calories and is the unit used in describing the energy available from food.

Distinguish between temperature and heat.

Temperature is a measurement of how hot or cold an object is. Heat is the thermal energy stance to a cooler one.

Why is the West Coast of the United States warmer in winter than the East Coast?

The West Coast is warmer because air moves from the Pacific Ocean to the land and the ocean water is warmer than the air. This doesn't effect the East Coast because the direction of air is from the land to the Atlantic Ocean.

When you touch a cold surface, does cold travel from the surface to your hand or does energy travel from your hand to the cold surface?

The direction of energy travel is from hot to cold- from your hand to the cold surface. There is no "cold" that travels in the other direction.

Thermal expansion

The expansion of a substance due to increased molecular motion in that substance.

Why does a penny become warmer when struck by a hammer?

The hammers blow causes the coin's atoms to jiggle faster.

Absolute zero

The lowest possible temperature; the temperature at which all particles have their minimum kinetic energy.

Specific heat capacity

The quantity of heat per unit of mass required to raise the temperature of a substance by 1 degree Celsius.

heat

The thermal energy that flows from an object at higher temperature to one at a lower temperature, commonly measured in joules or calories.

thermal energy

The total energy (kinetic plus potential) of atoms and molecules that make up a substance.

What was the precise temperature at the bottom of Lake Superior on New Year's Eve in 2000?

The water at the bottom is 4 degrees Celsius year round.

What's inside the open spaces of the water crystals?

There is nothing at all in the open spaces.

What pressure would you expect in a rigid container of 0 degrees celsius gas if you cooled it by 273 degrees celsius?

There would be no pressure.

When you touch a cold surface, does "coldness" travel from the surface to your hand or does thermal energy travel from your hand to the cold surface? Explain.

Thermal energy travels from your hand to the cold surface because the direction of thermal energy flow is always from a warmer substance to a cooler one.

Which has a higher specific heat capacity, water or sand? In other words, which takes longer to warm in sunlight (or longer to cool at night)?

Water has the higher specific heat capacity.

How is bimetallic strip used to regulate temperature?

When a room becomes too cold, the coil bends toward the brass side and activates an electrical switch that turns on the heater. When the room gets too warm, the coil bends toward the iron side, which breaks the electrical circuit and turns off the heater.

What is meant by the statement, "a thermometer measures its own temperature"?

When a thermometer is in contact with something whose temperature we wish to know, thermal energy flows between the two until their temperatures are equal.

How does the law of the conservation of energy relate to the first law of thermodynamics?

When the conservation of energy is applied to thermal systems, we have the first law of thermodynamics.

A Concorde supersonic airplane is 20 cm longer when in flight than when parked on the ground. Offer an explanation.

At cruising speed (faster than the speed of sound), air friction against the Concorde raises its temperature dramatically, resulting in this significant thermal expansion.

Is the temperature of an object a measure of the total kinetic energy of molecules in the object, or a measure of the average kinetic energy per molecule in the object?

Average kinetic energy per molecule in the object.

Bermuda is close to North Carolina, but unlike North Carolina, it has a tropical climate year round. Why?

Bermuda is an island. The surrounding water warms it when it might be too cold, and cools it when its might be too warm.

Which will raise the temperature of water more, adding 4.18 joules or 1 calorie?

Both the same.

How is the energy value of foods determined?

By the energy released when they are burned.

What are the temperatures for freezing water on the celsius and fahrenheit scales? For boiling water at sea level?

Celsius is 0 degrees. Fahrenheit is 32 degrees.

True or False: Temperature is a measure of the total kinetic energy in a substance.

False. Temperature is a measure of the average kinetic energy of the molecules in a substance.

second law of thermodynamics

Heat never of itself flows from a cold substance to a hot substance.

When you can't loosen a metal lid o a glass jar, how can you use the concept of thermal expansion to rescue the situation?

Hold the lid of the jar under hot water for a few seconds. The metal should expand more than the glass, making it easier to loosen.

What determines the direction of heat flow?

Hot to cold.

How does the second law of thermodynamics relate to the direction of heat flow?

It states that heat never spontaneously flows from a cold substance to a hot substance.

Suppose you add a flame to 1 L of water and its temperature rises by 3C. If you apply the same flame for the same length of time to 3 L of water, by how much does its temperature rise?

Its temperature rises by only 1 degrees C.

which generally expands more for the same increase in temperature- solids or liquids?

Liquids.

Does a substance that heats up quickly have a high or low specific heat capacity?

Low specific heat capacity.

Which is larger, Celsius or a kelvin?

Neither. They are equal.

When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or a net contraction?

Net contraction (0-4C) then expansion.

Third law of thermodynamics

No system can have its absolute temperature reduced to zero.