1. Several themes are recurrent
Themes for GEOG/PHYS 182:
Force
Energy
Field
Equilibrium
Diffusion

2. Force
Force – Any interaction that tends to change the motion of an object.
-Intuitively a push or pull
Four types of fundamental forces:
Gravitational
Electromagnetic
Weak
Strong (Nuclear)
SI unit of force: N (newton)

3. Newton’s Laws of Motion
Newton’s first law: A moving object will continue moving in a straight line at a constant speed, and a stationary object will remain at rest, unless acted on by an unbalanced force.
Newton’s second law: The acceleration produced on a body by a force is proportional to the magnitude of the force and inversely proportional to the mass of the object.
Newton’s third law: For every action there is an equal and opposite reaction.
for two bodies, A and B

4. Work and Energy
Energy – A property of objects, transferrable among them via fundamental interactions, which can be converted into different forms, but not created or destroyed.
Some types of energy:
Kinetic energy – energy associated with motion
Potential energy – stored energy (many types) -spring, battery, ball at top of hill
Heat energy
SI unit of energy: J (joule)
Work – Force exerted on an object times the distance over which it is exerted. Equation form: W=Fd
SI unit of work: J (joule)

5. Fields
Field – A physical quantity that has a value for each point in space and time.
There are two types of fields in physics: 1) Vector field – both a magnitude and direction specified for each point in the field. -Field lines used to show the strength and direction in space Examples: Gravitational field, electric field, magnetic field 2) Scalar field – have only a magnitude for each point in the field. -Contour lines used to show regions where the magnitude is the same Examples: Temperature distribution in a room, pressure distribution in a fluid, voltage surrounding an electric charge

6. Gravitational field and force between masses:
Electric field and force between charges:

7. Magnetic field lines:
Earth’s magnetic field
Bar Magnet
Current carrying loop
Iron filings around bar magnet

8. Equilibrium of mechanical systems
Equilibrium - The condition of a system in which all competing influences are balanced, in a wide variety of contexts.
Mechanical Equilibrium – A state in which the sum of all of the forces and the sum of all of the torques acting on a body are equal to zero.
Condition 1: Sum of forces in every direction is zero
Condition 2: Sum of all the torques acting on a body is zero
Torque – The tendency of a force to rotate an object about an axis

10. Classifications of Equilibrium Points

11. Diffusion Diffusion – The net movement of a substance from a region of
high concentration to a region of low concentration (also, movement of a substance down a concentration gradient). Gradient – Direction of greatest rate of increase. Change over a distance
Examples: 1) Peeling orange, opening tuna can
2) Vacuum pump
3) Dye drop in water

12. Conservation Principles in Physics
Conservation Principles – For isolated systems, certain quantities are held constant during its evolution.
-These fundamental laws are often the starting point for solving problems in physics
Examples of conserved quantities: 1) Conservation of energy
2) Conservation of linear momentum
3) Conservation of angular momentum
4) Conservation of electric charge