Physical SciencePhysics
OGT Prep
Newton’s Laws of Motion
Newton’s 1st Law
(The Law of Inertia) An object at rest tends to stay at rest and an
object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force
1st Law Example
Why is it so important to wear a seatbelt?
Seat belts are used to provide safety for passengers whose motion is governed by Newton's laws. The seat belt provides the unbalanced force which brings you from a state of motion to a state of rest safely.
Newton’s 2nd Law
The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.
Force = Mass x Acceleration
F = M x a
2nd Law Example
Picture a big car and a small car. The bigger car obviously has more mass than the small car. If you give them the same force (the same push or pull), won’t the big car move (accelerate) less?
Newton’s 3rd Law
For every action, there is an equal (in size) and opposite (in
direction) reaction force
3rd Law Example
An unfortunate bug strikes the windshield of a bus. The bug hit the windshield and the windshield hit the bug. Which of the two forces is greater: the force on the bug or
the force on the bus?
Key Terms
Force: any push or pull
Friction: force which resists motion or attempted motion
Weight: the force due to gravity on a body (object)
Law of Conservation of Energy
In any physical or chemical change, energy is neither
created nor destroyed
It can only be transformed from
one form of energy to another
Energy
Potential Energy: stored energy. The energy is stored by doing work against a force such as gravity, a spring in a clockwork motor, or even an electromagnetic field.
– energy of position
Kinetic Energy: energy that a body possesses as a result of its motion.
– defined as work needed to accelerate a body from rest to a velocity - energy of motion
Potential Energy
Potential/Kinetic Energy
Physical ScienceChemistry
Physical and Chemical Properties of substances
Physical Properties– Can be observed w/o
changing the identity of the substance
Density Melting point Boiling point Color Mass
Chemical Properties– Describes how
substances change into new substances either by combining w/ other elements or breaking apart into new substances
Flammability Reactivity
Physical and Chemical Changes
Physical Changes – Phase changes
Freezing, melting, boiling
– Dissolving– Can be reversed
Chemical Changes– Change in color or odor– Production of sound, heat,
or light– Cannot be reversed
without LOTS of energy
Important terms in Chemistry
Elements – substance that cannot be separated or broken down into simpler substances by chemical means
Protons – subatomic particle with positive charge, mass of 1. Located in the nucleus of an atom
Neutrons – subatomic particle with no charge, mass of 1. Located in the nucleus of an atom
Electrons – subatomic particle with negative charge, has no mass
The Atomic Number is the main number of the element signifying the number of protons.
The Atomic Mass is the average mass of the element in its most stable form. This takes into account both protons and neutrons. Electrons have no mass.
Atomic Number
Symbol
Element Name
Atomic Mass
Isotopes
Atoms of the same element may have different numbers of neutrons. This causes different masses (atomic mass) BUT has no effect on charge.
For example, all carbon atoms have 6 protons (atomic number is 6). The number of electrons depends on the charge and the number of neutrons depends on the atomic mass. C-14 has 6 protons and 8 neutrons.
Ions
Common Question
How many protons, neutrons, or electrons are in the following element if it is +1 in charge:
30
Zn
Zinc
65.409
Experiments in Chemistry
Safety is always number one concern!!
Goggles are worn for every experiment
Common OGT experiments include experimenting with Acids and Bases
Acids, Bases, and the pH scale
pH is measurement of a liquid to determine if it is acidic, basic, or neutral.
The scale goes from 0-14 Low numbers (0-6) are Acidic High numbers (8-14) are Basic 7 is Neutral and is the pH of pure water
Acids and Bases:
Acids:– Low pH (0-6)– Sour Taste– Conduct electric current– Corrosive– Can damage materials
and skin Examples:
– Lemon juice– Stomach acid
Bases:– High pH (8-14)– Bitter Taste– Very slippery feeling– Conduct electric current– Can damage materials
and skin Examples
– Soap, many cleaners– Fertilizer– Milk