PSC 1121: Physical Science
Definitions
science – systematic knowledge accumulated in our effort to answer questions
pseudoscience – claims presented so that the appear to be scientific even though they lack supporting evidence and plausibility
theory – collection of laws that can be tested and proved, tested and disproved, or untested
Ferni problems (back-of-envelope problems) – approximations done quickly using basic measurements
vector – straight piece of a line with beginning and end
*Used with velocity and forces
impulse – a force acting on an object for a period of time
static equilibrium – forces cancel each other out
completely inelastic – all energy is turned to heat
work – mediator of one form of energy to another
power – how fast you work
center of mass – the average position of all the mass that makes up the object
center of gravity – the average position of weight distribution
torque – the tendency of a force to cause rotation
Collisions:
energy – another way to review motion and the possibility to move
elastic – no energy turned to heat
inelastic – some energy is lost to heat
Formulas
· Average Speed = distance/duration
· Velocity: v = d/t
· Acceleration: a = change in speed/change in time
· Momentum: p = mv
· Impulse = F·t
· KE = (1/2)mv²
· PE = mhg
· F=ma
· Fc = mw²r
· Fc = (mv²)/r
· v = rw
· w = theta/time
· g = w²r
· Gravity: F=G(m1m2)/d2
Units
Speed: mph, m/s, km/h, etc.
Velocity: m/s, km/h, etc.
Acceleration: m/s2, km/h2, etc.
Momentum: kgm/s
Impulse: N·s
Rotational Speed: radians/s
Random Measurements
· Apple = 1 N
· Human = 1 m
· Trees = 10 m
· Football Stadium = 100 m
· Molecules: 10-9 m (1 billionth of a meter/nano-)
· Atoms: 10-10 m (10 billionth of a meter)
· Nucleus: 10-15-10-14 m
· Hiroshima Bomb: 5·1013 J
· Earth’s radius: 6500 km
· Mass of an average person: 80 kg
Scientific Method
1. Observe
2. Hypothesize
3. Experiment
4. Conclude
Forces
· Push or pull
· Fundamental Forces:
o Electro-magnetic
o Weak Interaction
o Strong Interaction
o Gravitation
Gravity
· The shapes of movement that gravity can create:
o Straight line
o Circle
o Ellipse
o Parabola
o Hyperbola
Angular Momentum
· Depends on
o Magnitude of the force
o The direction in which it acts
o The point at which it is applied on the object
Laws and Theories
· Theory of Everything: the idea that all things can be explained through science
· Newton’s Laws of Motion
1. Law of Inertia – an object at rest will stay at rest and an object in motion will stay in motion unless acted upon by a force
2. The acceleration of an object depends on the object’s mass and the amount of force applied
3. Every action has an equal opposite reaction
· Conservation Laws: a quantity remains the same all the time no matter what happens to a system
o Momentum: momentum remains the same in a system – the amount of momentum at the beginning has the same momentum at the end
· Kepler’s Laws of Gravity
1. The planets orbit the Sun in ellipses with the Sun at one focus
2. The line joining the Sun and the planet sweeps out equal areas in equal times
3. The period of the planet and the size of the ellipse relate
Important Notes
· Everything is relative
· Never write a number without its units
· If it cannot exchange particles, it does not exist
· Perpetual machine is impossible since you cannot “make” energy or momentum
· Spinning stations could emulate artificial gravity
· Angular Momentum: Torque :: Momentum : Force
· Think of how changing values will change in the context of a formula
Random Facts
· 70% of Americans lack a clear understanding of the scientific process
· Psychology has the least believers in pseudoscience
· The universe is over 14 billion years old
· 99.999999999999% of an atom’s volume is empty space
· If protons and neutrons were a centimeter, electrons and quarks would be less than the diameter of a hair. The atom’s diameter would be greater than the length of 30 football fields
· ISU is not metric
· Imperial system was based on body parts
· Daytona racetrack has a 31° bank