The difference between scalars and vectors is that scalars have magnitude only while vectors have magnitude and direction .
Speed is a scalar while velocity is a vector. They are different because velocity uses direction and speed doesn’t.
When you add vectors the final vector is known as the resultant .
When you break a vector down into its parts the parts are known as components .
Component vectors are always either horizontal or vertical .
Acceleration is a change in velocity , direction, or both .
Speed and distance are both scalars, while velocity and displacement are both vectors .
As an object accelerates at a constant rate its velocity increases at a constant rate.
As an object accelerates at a constant rate its displacement increases at an exponential rate.
The equation v = d/t can only be used if an object is traveling at a constant rate or if you are finding the object’s average velocity.
The equation v = d/t can never be used (by itself) if an object is accelerating .
If a graph of displacement vs. time has a positive linear slope that means the object is traveling at constant velocity .
If a graph of velocity vs. time has a positive linear slope that means the object is accelerating .
If an object is moving with a constant positive acceleration the graph of acceleration vs. time is linear and positive .
If an object is slowing down at a constant acceleration the shape of a velocity vs. time graph will have a negative linear slope.
A force causes an object to accelerate .
A net force is what you get when you combine all of the forces acting on an object.
A net force of zero is acting on an object. That means that the object is not accelerating .
An object with a net force of zero means the object is at constant velocity .
The symbol µ stands for coefficient of friction .
The larger the value for µ the more friction is present.
Weight is dependent on mass and gravity .

When working with mass and weight, a mass is a scalar while weight is a vector .
When working with a constant force, mass and acceleration are inversely proportional.
Friction is a type of force .
If an object is on an incline there are 4 forces acting on the object at once. Those forces are friction, parallel , normal , and resultant .
A normal line is always perpendicular to a surface.
On a flat, horizontal surface a normal force is always equal to weight .
On an incline an object will not slide down the incline until the parallel force is equal to or larger than the friction force.
As the angle of an incline increases the normal force decreases , the parallel force increases , and the weight remains constant .
The unit of force is the newton .
The unit of acceleration is m/s 2 .
The unit of mass is kg .
An object is a projectile when it is unpowered and the only thing acting on it is gravity .
Gravity is an acceleration that creates a force on objects.
With any projectile the horizontal component of the projectile’s velocity is constant .
Affecting the vertical component of a projectile’s velocity is gravity .
All projectiles travel in the path of a parabola (trajectory) .
The range of a projectile is how far it travels horizontally .
The velocity of a projectile at its highest point is equal to the projectile’s horizontal velocity.
At its highest point the acceleration of a projectile is equal to 9.8m/s 2 (gravity) .
The horizontal component of a projectile’s velocity is not affected by gravity since gravity only acts vertically .
The three main variables that determine how long and how far a projectile can travel in the air are velocity , angle of launch , and friction (air resistance) .
Momentum is a vector quantity.
Impulse causes a change in momentum on an object.

The addition of all momentums in a system and the fact that the sum does not change is the definition of conservation of momentum .
Impulse works on individual objects while conservation of momentum works with systems .
Objects lose momentum mainly due to the presence of friction .
The most common unit for momentum is kgm/s .
Kinetic energy is the energy of motion .
Potential energy is the energy of position .
Potential and kinetic energy are both forms of mechanical energy.
Work is a form of energy .
Work is done when a force causes an object to move a distance .
Work is done any one or combination of 3 ways. Lifting an object against gravity , overcoming friction , or causing an object to accelerate .
Potential and kinetic energy are measured in joules .
You know an object has potential energy if it has height .
You know an object has kinetic energy if it has velocity .
Work is measured in joules .
Energy is neither created nor destroyed it can only change forms is known as conservation of energy .
Conservation of energy and/or momentum means that however much you start with is how much you end with.
If a person has more power than another that means the person can do more work in the same amount of time .
Machines are never 100% efficient because of the presence of friction .
The three ways that a machine can change a force are the size , speed , and the direction .
Energy is defined as the ability to do work .
The joule is the SI unit of work.
Power is the rate at which work is done, and it is measured in watts .
As the friction in a machine goes up, its efficiency goes down.
A system in simple harmonic motion is always trying to return to the equilibrium .
A spring possesses elastic potential energy.

Frequency is defined as oscillations per second.
Maximum displacement from equilibrium is called amplitude .
Period and frequency are inversely related.
Hertz is the proper unit of frequency.
The time for an object to complete a single oscillation is called the period .
An object in circular motion is always accelerating towards the center .
Two different objects on a rigidly spinning body will always have the same rotational speed, but could have different linear speeds depending upon their positions.
A centripetal force is a center-seeking force.
Opposite charges attract each other, like charges repel each other.
An ion is a charged atom, which can occur if it gains or loses electrons .
The Si unit of charge is the coulomb .
Gravity, electrical, and magnetic are all field forces since they act at distances.
Gravity is always a force of attraction , while the electrical force can also be a force of repulsion .
The ampere is the proper unit for current.
An electrical circuit with only one possible path is called a series circuit.
Adding resistors in series increases the overall resistance in the circuit; adding resistors in parallel decreases the overall resistance in the circuit.
Electrical resistance is measured in ohms ; while the potential difference is measured in volts .
Electrical resistance and current are inversely related.
The SI unit of electrical power is the watt .
The length of a wire and its resistance are directly related.
A step-up transformer increases the voltage by having more loops of wire on the secondary (out-going) side than on the primary (in-going) side.
In a series circuit the current is constant in all parts of the circuit.
In all paths of a parallel section of a circuit, the voltage drop is the same.
Luminous means that an object produces its own light.

An object that is illuminated reflects light that strikes it.
Light is an electromagnetic wave that shows properties of transverse waves.
Sound is a mechanical wave that shows properties of longitudinal waves.
When an object allows light that strikes it to pass through, the object is said to transmit the light.
An opaque object does not transmit any light that strikes it.
Transparent means that an object can be seen clearly through.
A convex lens is also known as a converging lens.
A concave lens is also known as a diverging lens.
An image that cannot show up on a screen is known as a virtual image.
Dispersion is the spreading out of light as it passes through a material.
The bending of light waves as they pass from one medium into another is called refraction ; it is caused because the light changes speed as it changes mediums.
Reflection is the bouncing of light rays.
The law of reflection says that the angle of reflection always equals the angle of incidence.
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If light is traveling from a less dense into a more dense medium, the angle of refraction will be smaller (less) than the angle of incidence.