Physics: Heat Assessment

Radiation

- the transfer of thermal energy by electromagnetic radiation - does not require a medium

Units for measuring energy

joules calories BTUs

Metal Specific Heat Metal Specific Heat aluminum 900 J/kgC° mercury 140 J/kg.C° copper 385 J/kg.C° sand 664 J/kg.C° Which substance would require the most heat to raise the temperature of 1,000 g 1°C? A. aluminum B. mercury C. copper D. sand

aluminum

1 calorie equals...

= 0.001 kcal = 4.186J

1 Joule equals...

= 0.239 cal = 0.000239 kcal

1 kcal equals...

= 1,000 cal = 4186

1 kcal is

Calorie (Cal), or dietary calorie

Which two temperature scales are a US scientist most likely to use in his or her work? A. Fahrenheit and Kelvin B. Fahrenheit and Celsius C. Celsius and Kelvin D. Kelvin and joule

Celsius and Kelvin

temperature scales

Fahrenheit, Celsius, and Kelvin

Which of the following correctly describes heat? A. Heat is thermal energy flowing from a lower temperature object to a higher temperature object. B. Heat is thermal energy flowing from a higher temperature object to a lower temperature object. C. The total heat contained in an object is the same as its temperature. D. Heat is the total amount of energy associated with an object.

Heat is thermal energy flowing from a higher temperature object to a lower temperature object.

Heat

a measure of thermal energy in transit

objects that have different masses and/or different specific heats

may require different amounts of thermal energy to reach the same temperature

Increased kinetic energy increases the temperature, except at _____________. In this case, the temperature is __________ while the ___________ is accomplished.

phase-change points constant phase change

example of radiation

the warmth felt near a hot fire

Convection is the transfer of ________ along with moving matter. A. thermal energy B. radiation C. phase changes D. specific heat

thermal energy

Heat transfers energy until __________ is reached.

thermal equilibrium

The specific heat of a material is the amount of energy required A. to induce a phase change in the material. B. to bring the material to 0°C. C. to move it with a force of 1 N over a distance of 1 m. D. to change 1 g of the material by 1°C or 1 K.

to change 1 g of the material by 1°C or 1 K.

example of conduction

heating one end of an iron bar. Soon, the other end of the bar becomes hot

If one end of an iron bar is heated, what causes thermal energy to transfer to the other end? A. convection B. conduction C. radiation D. heat of fusion

conduction

At the phase-change points, the temperature remains _________ until the _________ is complete.

constant phase change

The SI unit of measure for thermal energy is a A. calorie B. joule C. BTU D. degree Celsius

joule

The common units used to measure thermal energy

joules (J) and calories (cal)

As energy is added to a substance, either the _______________ or ________________.

kinetic energy of its particles increases a phase change happens

The "kcal" unit is A. a kilogram calorie B. 1,000 calories C. 0.001 calories D. different from a dietary calorie

1,000 calories

Larger units of kilojoules (kJ) and kilocalories (kcal) are also used. They are_________ times larger than joules and calories, respectively.

1000

Which tool would be used to measure the changes in thermal energy of an object? A. hydrometer B. calorimeter C. specific heat meter D. can't measure it

calorimeter

Metal Specific Heat Metal Specific Heat aluminum 900 J/kgC° mercury 140 J/kg.C° copper 385 J/kg.C° sand 664 J/kg.C° One substance gave off 2695 J of heat when a 1,000. g mass of it had its temperature lowered by 7.0°C. This substance was A. aluminum B. mercury C. copper D. sand

copper

Which of the following is not a unit of energy? A. degree Celsius B. calorie C. kilocalorie D. joule

degree Celsius(it's a unit of temperature)

The flow of thermal energy from an object at a high temperature to one at low temperature is called . A. potential energy B. heat C. work D. temperature

heat

Thermal energy flows from________ temperature to__________ temperature.

higher lower (No process allows the reverse without work being done in an isolated system.)

Thermal energy

the total kinetic energy of the particles that make up a substance

example of convection

the upward flow of air above a room heater

The total energy of the particles that make up an object is A. kinetic energy B. temperature C. thermal energy D. specific heat

thermal energy

Explain the difference between thermal energy and temperature.

thermal energy = total KE (adding it changes temp or state) temperature =average KE

Which of the following cannot be the only movement of thermal energy in an isolated system? A. thermal energy transferred from a hotter object to a colder object B. thermal energy transferred from a colder object to a hotter object C. thermal energy transferred from one object to another D. temperature changes among the system's objects

thermal energy transferred from a colder object to a hotter object

In the context of heat, radiation is the transfer of ________ by ________. A. heated fluids; convection B. molecular kinetic energy; conduction C. heat; phase changes D. thermal energy; electromagnetic radiation

thermal energy; electromagnetic radiation

The warmth felt next to a hot fire is mainly due to ________. A. convection of air heated by the fire B. thermal radiation emitted by the fire C. conduction of heat through the air D. the visible radiation changing to heat as it shines on surfaces

thermal radiation emitted by the fire

The specific heat of a material is the amount of energy required A. to induce a phase change in the material. B. to bring the material to 0°C. C. to move it with a force of 1N over a distance of 1m. D. to change 1g of the material by 1°C or 1K.

to change 1g of the material by 1°C or 1K.

Thermal energy is transferred by

transferred by conduction, convection, and radiation

To solve calorimetry problems

use the principle of the conservation of energy in an isolated system and the specific heat equation Q = mcΔT.

Which of the following can cause objects to require different amounts of thermal energy to reach the same temperature? A. different materials B. different specific heats C. different masses D. all of the above

all of the above

An object with a specific heat of 525 J/kg.C° goes through a temperature change of 5°C. What additional information would you need to calculate the change in thermal energy? A. initial temperature of the object C. mass of the object B. final temperature of the object D. volume of the object

mass of the object

Metal Specific Heat Metal Specific Heat aluminum 900 J/kgC° mercury 140 J/kg.C° copper 385 J/kg.C° sand 664 J/kg.C° Fifty grams of each substance are placed in an oven. After 15 minutes of heating, which substance would go through the greatest temperature change A. aluminum B. mercury C. copper D. sand

mercury

Thermal energy is being steadily added to a system. Which two effects do not occur at the same time? A. change of state and phase change B. average kinetic energy increase and temperature increase C. phase change and temperature increase D. total kinetic energy increase and phase change

phase change and temperature increase

Thermal energy is being steadily added to a system. Which two effects do not occur at the same time? A. change of state and phase change B. average kinetic energy increase and temperature increase C. phase change and temperature increase D. total kinetic energy increase and phase change

phase change and temperature increase

One calorie is the amount of energy required to ________. A. exert a force of 1 N over a distance of 1 m B. raise the temperature of 1 kg of water by 1°C C. raise the temperature of 1 g of water by 1°C D. change the state of matter of 1 g of water

raise the temperature of 1 g of water by 1°C

One calorie is the amount of energy required to________. A. exert a force of 1N over a distance of 1m B. raise the temperature of 1 kg of water by 1°C C. raise the temperature of 1 g of water by 1°C D. change the state of matter of 1 g of water

raise the temperature of 1 g of water by 1°C

Adding thermal energy to a substance either increases its________ or changes its_________.

temperature state

Specific heat

the amount of energy required to raise the temperature of 1 g of the material by 1ºC

Which physical principle is the main foundation for solving thermal energy transfer problems for a particular system? A. the law of conservation of energy B. mass balancing C. conservation of temperature D. temperature averaging

the law of conservation of energy (the first law of thermodynamics)

Calorimetry

the study of the thermal-energy transfer between different substances

Calorimetry is ________. A. changing calories into metric units B. the measurement of heat imparted to substances from calorimeters C. the study of thermal energy exchange during thermodynamic processes D. the comparison of calories with the amount of heat represented by other units

the study of thermal energy exchange during thermodynamic processes

Which of the following correctly describes heat? A. when the substance is in it gaseous state B. when the substance is undergoing a phase change C. when it has reached its specific heat capacity D. when its molecules are gaining kinetic energy

when its molecules are gaining kinetic energy

When does the flow of thermal energy stop? A. when the objects are in thermal equilibrium B. when all the thermal energy has transferred to the cooler object C. when the cooler object cannot absorb more thermal energy D. when the objects have both changed temperature by the same amount

when the objects are in thermal equilibrium

When does the flow of thermal energy stop? A. when the objects are in thermal equilibrium B. when all the thermal energy has transferred to the cooler object C. when the cooler object cannot absorb more thermal energy D. when the objects have both changed temperature by the same amount

when the objects are in thermal equilibrium

Under what conditions does thermal-energy transfer between objects at different temperatures?

- The objects must be in thermal contact. - Hot to cold

Temperature

- a measure of the average kinetic energy of the particles in a substance - tells how "hot" or "cold" something is

Convection

- energy transfer by moving matter - works with fluids (liquids and gases). - does not work in a vacuum

0.239 cal is equivalent to ________. A. 1 J B. 239 kcal C. 1 kJ D. 239 J

1 J

Which of the following can cause objects to require different amounts of thermal energy to reach the same temperature? A. different materials B. different specific heats C. different masses D. all of the above

all of the above

Thermal energy added during a phase change

allows the particles to overcome the intermolecular forces holding them together instead of increasing their kinetic energy

Conduction

- happens within a substance - Energy applied to one area moves to other areas - Particles transfer kinetic energy by way of collisions - works best with solids - works less well with liquids and not well with gases - It does not work in a vacuum.

Explain how putting a block of metal and a block of wood in the freezer is an example of heat. Even though they would both eventually reach the same temperature, the metal would cool down faster - explain why. If you grabbed them both out of the freezer after they were the same temperature, the metal would feel "colder" - explain why?

-2 things of different temperatures coming into contact and exchanging heat(def. of heat) -metals have lower specific heat -metals are conductors (heat flows in and out faster)

0.239 cal is equivalent to________. A. 1 J B. 239 kcal C. 1 kJ D. 239 J

1 J

The energy required to raise the temperature of 1 kg of water by 1°C is A. 1 J. B. 1 K. C. 1 cal. D. 1 kcal.

1 kcal.

The "kcal" unit is A. a kilogram calorie B. 1,000 calories C. 0.001 calories D. different from a dietary calorie

1,000 calories

The emission and absorption of electromagnetic radiation results in the transfer of thermal energy. The best example of this is ________. A. a microwave oven B. a pot sitting on a stovetop burner C. a convection space heater D. a fan

a microwave oven

The SI unit of measure for thermal energy is a A. therm B. joule C. BTU D. degree Celsius

joule

A=200g and 50˚C B=200g 70˚C C=400G 70˚C Assuming beakers A, B and C all contain pure water, which beaker contains water molecules with the greatest average kinetic energy? A. beaker A B. beaker B & C C. beaker C D. the average kinetic energy is equal in all three

beaker B & C

Which of the following is the best example of convection? A. hot air naturally flowing upward above a heater B. the handle end of a metal spoon in a pot of boiling water becoming hot C. the warmth felt next to a lit incandescent light bulb D. a black asphalt driveway becoming hot in the Sun

hot air naturally flowing upward above a heater

During a phase change, as energy is added, the temperature of a substance ________. A. increases B. is constant C. decreases D. first increases and then decreases to its original value

is constant

During a phase change, as energy is added, the temperature of a substance ________. A. increases B. is constant C. decreases D. first increases and then decreases to its original value

is constant

When energy is added to a substance at constant volume and pressure, its temperature increases except ________. A. when the substance is in it gaseous state B. when the substance is undergoing a phase change C. when it has reached its specific heat capacity D. when its molecules are gaining kinetic energy

when the substance is undergoing a phase change