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