Physical Science Physics OGT Prep

Newton’s Laws of Motion

Newton’s 1 st 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 unless acted upon by an unbalanced force

1 st 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 2 nd 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.net force Force = Mass x Acceleration F = M x a

2 nd 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 3 rd Law For every action, there is an equal (in size) and opposite (in direction) reaction force

3 rd 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 velocitywork - energy of motion

Potential Energy

Potential/Kinetic Energy

Physical Science Chemistry

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

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