Page 27 - Laboratory Manual in Physical Geology

force that you physically exerted on the ruler. The amount bonds (chemical energy) within the sugar molecules.
of energy stored in the ruler is the same as the amount of When you eat sugar, your body breaks the chemical
energy that you exerted to bend the ruler. bonds so the energy can be transformed into heat energy,
electrical energy, and other forms of chemical energy
■ Kinetic energy is the energy that an object has due used to energize, grow, and repair cells. In an earthquake,
to its motion. Because the object is moving, it has the potential energy stored in rocks is transformed into kinetic
ability to do work (when it hits another object). You energy, which leads to the quaking motion of pushes and
can tell that a moving car has kinetic energy because it pulls that you feel and call an earthquake. Many energy
is moving and has the capacity to do work when it hits transformations are associated with pushes and pulls (also
something.
called forces).
■ Mechanical energy is the sum of energy associated
with the motion (kinetic energy) and position Energy, Matter, and Force
(potential energy) of an object. A force is a push or a pull. For example, the force of gravity
■ Chemical energy is the energy stored in bonds of (the mutual attraction between two objects) pulls us
molecules and chemical compounds. The glucose towards the center of Earth. Magnetic force has polarity.
sugar in your body stores energy that is released when Unlike poles attract (pull the magnets together), and like
its bonds are broken during respiration. poles repel (push the magnets apart). As a force pushes or
pulls, it causes objects to build up potential energy, start
■ Electrical energy is the energy carried by a flow moving, change direction of movement, or stop moving.
of electrons, as in lightning and electrical currents Unlike matter, which you can see and feel, you cannot see
flowing through wires and circuit boards in your a force. But you can feel the push or pull of a force, and
electrical devices. you can see how it affects the motion or change in shape
(deformation) of objects. When a force acts on matter, the
matter has potential energy (energy stored in an object
Energy Transfer and Equilibrium
because of its position in a force field) or kinetic energy
Energy cannot be destroyed or used up, but it can be (the capacity to work as a function of its motion). So when
transferred from a source (place with more energy) to a sink we say that energy is the capacity to do work, it means
(place with less energy). For example, energy from the Sun that energy is the potential to exert a force. The force is
(a source) is transferred to Earth (the sink) by radiation what does the moving. The force also transfers energy and
(transfer of energy through space; not via materials), just transforms energy.
as you can feel heat energy radiating from a hot stove. When you push a heavy object, some of your chemical
Energy from Earth’s core (source) is transferred to the energy is converted to mechanical energy, which powers
mantle above it (the sink) by conduction (energy transferred the force. During the force, the mechanical energy is
by direct contact between molecules of two stationary transformed into potential energy until the object moves
materials), just as you feel heat energy being conducted (whereupon it is transformed into kinetic energy). When
into your hand when you pick up a pan by its hot handle. you stop pushing, there is no more force (the force is
Energy from Earth’s core is also transferred to the mantle destroyed), but the energy was transformed and conserved
by convection (energy transferred or conveyed in moving (not created or destroyed). This is a basic law (fundamental
molecules of flowing materials), just as you can see energy principle) of nature. Of course, matter cannot be created
being transferred by convection in the motion of boiling or destroyed either, so the two concepts are combined into
water or in the hot globs of lava moving in a lava lamp. one law. The Law of Conservation of Matter and Energy is
If energy of the source equals energy of the sink, then that matter and energy can be transferred and transformed
energy transfer stops, and the relationship is said to be but cannot be created or destroyed.
in equilibrium . For example, if you turn off a boiling pot
of water, its thermal energy will be dispersed into the
materials around it until the pot of water and everything Processes and Cycles of Change
else in the room reach the same temperature (room Earth is characterized by the transfer (flow) of matter
temperature). When they reach room temperature, they (materials) and energy during processes of change
are in thermal equilibrium. ( FIGURE 1.6 ) at every spatial and temporal scale of

observation. Most of these processes involve organic
Energy Transformation (biological; parts of living or once living organisms) and
When you sit in sunlight, you feel the Sun’s energy inorganic (non-biological) materials in solid, liquid, and
being transformed into heat. Plants transform the Sun’s gaseous states, or phases . Note that many of the processes
electromagnetic energy into chemical energy to make their have opposites depending on the flow of energy to or
food. The plants apply the chemical energy when they use from a material: melting and freezing, evaporation and
it to do work (cause an action; use it in photosynthesis condensation, sublimation and deposition, dissolution
to transform water and carbon dioxide into their food: and chemical precipitation, photosynthesis (food energy
C H O , glucose sugar). Energy is stored as chemical storage) and respiration (food energy release or “burning”
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