how far an object will go in a certain amount of time

ie: 100 km/hour, 60 miles/hour, etc. 

- tells both the speed and direction of an object

ie: 100 km per hour going due north 

- an object has acceleration if its velocity is changing in any way (whether in speed, direction or both)

ie: speeding, turning and slowing down 

- the acceleration of a falling object on earth 

- downward velocity increases by 10 meters per second per second (10 m/s with each second)

- abbreviated g

-

- an object's momentum is the product of its mass and its velocity 

- mass x velocity = momentum

- the only way to change an object's momentum is to apply a force to it

- a change in momentum occurs only when the net force is not zero 

- aka: overall force

- the combined effect of all the individual forces on an object (ie: the force of gravity, the force of electromagnetic forces, etc) 

- the amount of matter in your body (remains the same regardless of gravitational pulls/forces)

- the force that a scale measures when you stand on it 

- depends on both your mass and the forces (including gravity) acting on your mass

- falling without any resistance to slow you down 

- when you free fall you are weightless

- astronauts in orbit are weightless because they are in a constant state of free-fall

- NOT because there is zero gravity in space

- watched an apple fall to the ground . . had an epiphany 

- the same gravity that pulls that apple to earth also keeps the moon in orbit around the earth 

- eliminated Aristotle's distinction between the two realms (heaven & earth) and that they operate due to different laws/rules

- gave birth to the modern science of astrophysics 

Define/Describe:

NEWTON'S FIRST LAW OF MOTION

- in the absence of net force, an object will move with constant velocity. 

*ie: a spaceship needs no fuel to keep moving in space

- as long as an object is traveling at a constant velocity, no net force is acting on it. 

Describe/Define: 

NEWTON'S SECOND LAW OF MOTION

- tells us what happens to an object when a net for is present

- FORCE = MASS x ACCELERATION 

- explains why you can throw a rock further than you can throw a brick

- more massive planets exert a stronger gravitational force? (pg. 92, paragraph 2)

Describe/Define:

NEWTON'S THIRD LAW OF MOTION

- Every force is always paired with an equal and opposite reaction force

* explains rocket propulsion - a rocket engine generates a force that drives hot gas out the back, which creates an equal and opposite force that propels the rocket forward.

Define/Describe:

CONSERVATIVE MOMENTUM

- one of Newton's conservation laws

-the total momentum of all interacting objects always stays the same 

- an individual object can gain or lose momentum only when a force causes it to exchange momentum with another object. 

- conservation of angular momentum and conservation of energy are other conservation laws 

define/describe: 

ANGULAR MOMENTUM

- a special type of momentum used to describe objects turning in circles or going around curves

Angular Momentum of Earth = m x v x r 

m: earth's mass

v: earth's velocity

r: earth's radius of orbit 

define/describe:

THE LAW OF CONSERVATION OF ANGULAR MOMENTUM

- total angular momentum can never change 

- and individual object can only change its angular momentum by transferring some angular momentum to or from another object

What are the 2 key facts about earth's orbit that can be explained by understanding The Law of Conservation of Angular Momentum and the equation for Earth's angular momentum (angular momentum = m x v x r)

1. Earth will keep orbiting the sun as long as nothing comes along to take away its angular momentum 

- Earth needs no fuel or push to orbit the sun

2. Earth's angular momentum at any point depends on the product of its speed and orbital radius (distance from the sun) 

- therefore: Earth's orbital speed must be faster when it is nearer to the sun (radius is shorter) and slower when it is farther from the sun (radius is longer). 

- THIS IS CONFUSING: remember that angular momentum of the earth ALWAYS STAYS THE SAME, so if r (the radial orbit) is smaller, but the momentum is still the same, there must be an increase in the velocity (v) in order for the total product to remain the same. 

define/describe:

THE LAW OF CONSERVATION OF ENERGY

- energy cannot appear out of nowhere or disappear into nothingness

- objects gain or lose energy only be exchanging energy with other objects 

1. Kinetic (motion)

2. Radiative (light)

3. Potential (stored energy)

- energy of motion 

- examples: falling rocks, orbiting planets and molecules moving in the air

- energy carried by light 

- all light carries energy 

ie: light can change molecules in our eyes, allowing us to see

or warm the surface of the planet

- stored energy which may later be converted into kinetic or radiative energy 

ie: a rock on a ledge has gravitational potential energy, because it may fall

gasoline has chemical potential energy that may be converted into kinetic energy to make a car move

- calories (larger) 

- joules (smaller)

1 calorie = 4,184 joules

Define/Describe:

THERMAL ENERGY

- a subcategory of kinetic energy

- represents the collective kinetic energy of the many individual particles moving within a substance

- not the same thing as temperature 

- depends on temperature (higher average kinetic energy must lead to a higher total kinetic energy)

-depends on number and density of particles 

Thermal Energy: measures the total kinetic energy

Temperature: measures the average kinetic energy

define/describe: 

GRAVITATIONAL POTENTIAL ENERGY

- an object gravitational potential energy depends on its mass and how far it can fall as a result of gravity

- an object has more gravitational potential energy when it is higher than when it is lower

- kinetic energy increases as gravitational potential energy decreases 

- mass is a form of potential energy 

- called "Mass-energy"

define/describe:

MASS-ENERGY

- a form of potential energy 

- e = mc squared

e: amount of potential energy

m: that mass of the object

c: the speed of light

- small amount of mass contains a huge amount of energy 

-mass can be converted into energy and energy can be converted into mass

- the big bang

- the total energy content of the universe was determined in the big bang 

define/decribe:

NEWTON'S UNIVERSAL LAW OF GRAVITATION

(3 parts)

- every mass attracts every other mass through the force called gravity

- the strength of the gravitational force attracting any two objects is directly proportional to the product of their masses 

- doubling the mass of one object doubles the force of gravity between the two objects

-the strength of gravity between two objects decreases with the square of the distance between their centers 

- gravitational force follows an inverse square law

- doubling the distance between two objects weakens the force of gravity by 2 to the second power (4)