Pretestt

• Conduction–The transfer of heat or thermal energy by diffusion and collisions of particles within a substance due to a temperature gradient. By this process, heat is transferred through one substance to another when the two substances are in direct contact. For example, heat is transferred to a metal pot placed on a hot burner.

• Convection–The transfer of heat from one place to another by the movement of fluids. For example, when air heats up, the particles move farther apart and become less dense, causing the heated air to rise.

• Thermal radiation–The transfer of heat by radiation generated by the motion of charged particles. This method of heat transfer does not rely on any contact between the heat source and the heated object. For example, a person’s face is warmed by light radiated from the sun.

Thermal energy from a fire moves up through a chimney by

• Conduction

• Convection

• Thermal radiation

• Both convection and radiation

• Both conduction and convection

• Conduction–The transfer of heat or thermal energy by diffusion and collisions of particles within a substance due to a temperature gradient. By this process, heat is transferred through one substance to another when the two substances are in direct contact. For example, heat is transferred to a metal pot placed on a hot burner.

• Convection–The transfer of heat from one place to another by the movement of fluids. For example, when air heats up, the particles move farther apart and become less dense, causing the heated air to rise.

• Thermal radiation–The transfer of heat by radiation generated by the motion of charged particles. This method of heat transfer does not rely on any contact between the heat source and the heated object. For example, a person’s face is warmed by light radiated from the sun.

Thermal energy in a hot iron is transferred to a shirt by

• Conduction

• Convection

• Thermal radiation

• Both convection and radiation

• Both conduction and convection

Consider the following reaction:

4Al(s) + 3O₂(g) → 2Al₂O₃(s) + energy

This reaction is an _________ (exothermic/endothermic) reaction. Heat is _________ (absorbed, released) by the

reaction.

According to the law of conservation of energy, energy can neither be created nor be destroyed, only transferred and transformed from one form to another.

What kind of energy conversion is taking place when an electric bread toaster is switched on?

• Chemical → Electrical

• Electrical → Thermal

• Electrical → Sound

• Electrical → Chemical

Nuclear energy is obtained by nuclear fission, which is the process of splitting apart uranium atoms in a controlled manner that creates energy. This is quite dangerous because if the chain reaction of splitting the atoms is not controlled very carefully, an atomic explosion could occur. The fission process gives off heat energy, which is used to boil water in a power plant’s reactor core. The steam created with this water is used to turn a turbine, generating electricity.

Nuclear energy is derived from

• combustion of atoms of U-235

• fission of atoms of U-235

• fusion of atoms of U-235

• the breaking of U-235 bonds

Carrying capacity is the maximum number of individuals that can be sustained in a given environment at a given point of time. The following graph shows the effect of an overshoot of population on the carrying capacity of an area.

Which of the following situations best describes the graph?

• The overshoot of population never reached the carrying capacity.

• The overshoot of population had no effect on the carrying capacity.

• The population never stopped increasing, even after carrying capacity was reached.

• The overshoot of population caused the carrying capacity to decrease.