physics quiz (transfer of thermal energy)

which object loses all of its heat by radiation?

• a white plastic toy in the air at 100°C

• a shiny metal satellite at 30°C

• a metal block with black surfaces at 24°C in air

• the heating element of a kettle at 150°C in water

which of the following is the poorest conductor of thermal energy

• vacuum

• air

• white plastic block

• water

what heat transfer method is minimized because of the interior of a thermos bottle being silvered?

• conduction and radiation

• radiation

• convection

• convection and conduction

Which of the following best explains the scenario below? On a summer morning, John walks barefoot across his paved driveway with no problem. However, later that afternoon he steps barefoot onto the same driveway and must quickly run off because the bottoms of his feet feel like they are burning.

• As the temperature increased during the day, the particles in the pavement moved slower and the thermal energy increased.

• As the temperature increased during the day, the particles in the pavement moved slower and the thermal energy decreased.

• As the temperature increased during the day, the particles in the pavement moved faster and the thermal energy increased.

• As the temperature increased during the day, the particles in the pavement moved faster and the thermal energy decreased.

an insulator is a material that has molecules which

• closely packed together

• move easily past one another

• do not transfer heat easily

• do not impede the free flow of electrons

what is the purpose of the layer of vacuum in a thermo flask?

• to minimize convection

• to minimize radiation

• to minimize conduction

• to prevent the water from spilling

Energy transfer by convection is primarily referred to?

• fluids

• solids

• gases

• metals

heat transfer by conduction in metals occurs when

• atoms give off heat in the form of electro magnetic waves

• large numbers of atoms move from place to place

• electro magnetic waves travel from one place to another through a vacuum

• molecules then bump into nearby particles and transfer some of their energy to them

what are the changes when a fluid gets heated?

• the density of the fluid increases,causing them to fall and the particles gains more energy,causing them to vibrate more

• the density of the fluid decreases,causing them to rise and the particles gains more energy,causing them to vibrate more

• the density of the fluid increases,causing them to rise and the particles gains more energy,causing them to vibrate more

• the density of the fluid decreases,causing them to fall and particles gains lesser energy,causing them to vibrate more

When we heat a beaker on a tripod, a gauze is usually placed on the tripod. This is because the gauze

• Spreads the thermal energy evenly over the base of the beaker

• increases the rate of heating by becoming red hot itself

• Increases the rate of heating by conducting the heat faster

• Concentrates the thermal energy at one part of the base of the beaker