Physical Science Semester 1 Exam Review

Kilometer

Unit used to measure longer distances like the distance you would travel to another state for vacation.

Independent Variable

The variable that the experimenter changes in an experiment. Usually on the X axis of a graph.

Dependent Variable

The variable that the experimenter observes as a result of changing another variable.

Usually on the Y axis of a graph.

outlier

A data point that should be thrown out and measured again because it is very far off from the other measurements.

Scatterplot

A graph that shows the relationship between the independent and dependent variables.

Curved Line

Shape of the line on a distance vs time graph that shows acceleration.

Hypothesis

A prediction based on reasoning; It is specific and demonstrates the relationship between the independent and dependent variables often in the form of an if...then statement.

Speed

How fast an object changes position. How fast an object is moving.

Velocity

Speed with a specific direction.

Newton's 1st Law

An object in motion stays in motion with a constant velocity unless an external force acts on it.

Newton's 2nd Law

The force applied to an object is equal to the object's mass time acceleration.

Newton's 2nd Law fomula

F = ma

Force equals mass multiplied by acceleration.

Newton's 3rd Law

For every action there is an equal and opposite reaction; requires 2 different objects.

Net Force

Calculated by adding forces that act in the same direction or subtracting forces that act in opposite directions.

Vector

An arrow that shows both the magnitude and direction of an object in motion. Velocity is an example.

Gravity

Force of attraction between all masses in the universe. The downward Force on Earth. The distance between the objects and the mass of each object determent the pull between them.

Engineer

Uses scientific knowledge to design solutions to solve problems.

Scientist

Develops knowledge that allows us to understand the world and universe.

Potential Energy

Energy that is stored

Kinetic Energy

The energy matter has when it is in motion.

Work

= force x distance

When a force acts on an object and causes a displacement of that object.

Displacement must be parallel to the force.

Wavelength

The distance from crest to crest or trough to trough.

Doppler Effect

The perceived change in pitch when a sound approaches you or travels away from you. If moving toward you, the pitch will increase because the waves will be closer together (compressed). As it is moving away from you the pitch will decrease because the waves will be further apart (decompressed).

Reflection

When a light ray bounces off a surface.

Refraction

When a light ray bends as it passes through an object due to a change in speed. An example would be when light bends as it travel from air into water because it slows down in water.

Acceleration

Rate of change of velocity of an object.

Closed Circuit

A complete circuit. Electrons flow continuously without interruption. If a light bulb is attached, it will light up.

Open Circuit

The path of the electrons in this circuit has been interrupted or broken and the current will not flow. If a light bulb is attached, it will not light up.

Physical Science

The study of matter and energy, and the relationship between matter and energy.

Insulator

This slows heat transfer.

Equation to calculate Average Velocity

Distance / elapsed time

(d/t)

Kinetic Friction

Example: A box experiences this when it is pushed across a floor.

Air Resistance

Causes objects to fall at different rates. If this was not present (like in a vacuum) all objects fall at the same rate.

Density

Shown on a Mass vs. Volume graphs as the SLOPE of the line. This is higher for lines with steeper slopes.

Thermal Equilibrium

When 2 objects in contact with each other reach the same temperature.

Equation to calculate Potential Energy

= mgh

(m is mass, g is acceleration due to gravity, h is height)

Equation to calculate Kinetic Energy

= 1/2mV^2

(m is mass, V is velocity)

Examples of energy being transformed

1. when the brakes on a car heat up when used.

2. When a ball flies through the air.

3. When a sled goes down a hill.

4. When a pendulum swings back and forth.

In all, total energy stays the same.

Same amount of work

When a tool does the work faster, how much work is done compared to a tool that does it slower.

Mechanical Wave

Needs a medium to transfer energy; example sound or water waves.

Electromagnetic Wave

Does NOT need a medium to transfer energy; example light wave

Constructive Interference

When the crests of one wave overlap the crests of another wave.

Destructive Interference

When the crests of one wave overlap the troughs of another wave

Light

Described as a particle and a wave.

Order of Electromagnetic Spectrum

Longest to Shortest:

Radio - Microwaves - Infrared - visible- Ultraviolet - x-rays - Gamma

Parallel Circuit

A circuit that allows current to be sent through multiple paths. In a sting of lights, if one light goes out, the others stay lit.

Series Circuit

A circuit where there is only one path to and from the power source. In a string of lights, if one goes out then they all go out.

Voltage

The difference in electric potential energy between 2 positions.

Electric Current

The continuous flow of electric charge due to a difference in electric potential energy.

Resistance

The quality of a substance that hinders the flow of electrons through it.

Big Bang Theory

The contents of the known universe expanded explosively into existence from a hot, dense state 13.7 billion years ago. Evidence used to support this theory = Cosmic Background Radiation and Hubble's Law

Shapes of Galaxies

Spiral, Eliptical, Irregular