Astronomy Text 2- Chapter 4
gravity on earth:
9.8 m/s^2
the strength of gravitational force attracting any two objects is _____________ to product of their mass. For example, doubling the mass of _____ object doubles the force of gravity between the two objects
directly proportional one
Newtons 1st law:
an object moves at a constant velocity if there is no net force acting upon it objects at rest will remain at rest and objects in motion will remain in motion
Orbital angular momentum
angular momentum= Earths Mass x Orbital Velocity x Radius of its orbit
Angular momentum
any object that is spinning or moving along a curve path has angular momentum
rotational angular momentum
as long as earth isn't transferring any of the angular momentum of its to ration to another object it keeps rotating at the same rate
Conservation of angular momentum
as long as there is no external torque, the total angular momentum of a set of interacting objects cannot change
velocity
both speed and direction
gravitational potential energy
depends on an objects mass and how far it can fall as a result of gravity object will have more grab. potential energy when it is higher and less when it lower
Newtons laws of motion govern the
motion of everything from our daily movements on earth to the movements of planet, stars and galaxies throughout the universe
Force
only way to change an objects momentum
objects always get their energy from
other objects
net force
overall force
Momentum
product of its mass and velocity momentum=mass x velocity
thermal energy
represents the collective kinetic energy of the many individual particles moving randomly with a substance related to temperature
earth as ________________ angular momentum and sun has ________________ angular momentum
rotational and orbital
if something has _________ momentum it will not exert much force
small
3 terms used to describe motion in science
speed, velocity, acceleration
The strength of gravity between two objects decreases with the _______ of the distance between their centers
square
potential energy
stored energy two types:gravitational and chemical
Universal law of gravitation
strength of the gravitational attraction been two objects
Thermal energy depends on
temperature and the number and density of the particles
mass-energy
the amount of potential energy contained in mass E=mc^2
If you are standing on a scale in an elevator, what exactly does the scale measure? your mass the force you exert on the scale the gravitational force exerted on you by Earth
the force you exert on the scale
gravity accelerates all objects by ________
the same amount, regardless of their mass
Conservation of momentum
total momentum of interaction objects cannot change; their total momentum is conserved
Every mass attracts every other mass through the force called _______
Gravity
Joule
Standard unit of energy
As you found in Part A, your weight will be greater than normal when the elevator is moving upward with increasing speed. For what other motion would your weight also be greater than your normal weight? The elevator moves upward with constant velocity. The elevator moves downward with constant velocity. The elevator moves upward while slowing in speed. The elevator moves downward while slowing in speed. The elevator moves downward while increasing in speed.
The elevator moves downward while slowing in speed.
Suppose you visit another planet: Your mass and weight would be the same as they are on Earth. Your mass would be the same as on Earth, but your weight would be different. Your weight would be the same as on Earth, but your mass would be different.
Your mass would be the same as on Earth, but your weight would be different
if an object _____ its cause by momentum
accelerates
Acceleration of gravity
acceleration of a falling object
mass
amount of matter in your body
conservation of energy
energy cannot appear out of nowhere or disappear into nothingness objects can gain or lose energy only by exchanging energy with other objects
radiative energy
energy carried by light light can cause change in matter
energy
energy is what makes matter move
kinetic energy
energy of motion falling rocks, orbiting planets and the molecules moving in the air are all examples
free falling
falling without any resistance to slow you down
Newtons 3rd law
for any force there is always and equal and opposite reaction force
Weight
force that a scale measures when you stand on it depends on both your mass and the forces acting on mass
newtons 2nd law:
force=mass x acceleration
Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be __________. greater than your normal weight at rest equal to your normal weight at rest less than your normal weight at rest
greater than your normal weight at rest
Speed
how far something will go in a certain amount of time
acceleration
if speed or direction or both is changing
a planet has the least gravitational potential energy when
it is closest to the sun
Newton invented
laws of motion and gravity first reflecting telescopes mathematics of calculus
Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be __________. greater than your normal weight at rest equal to your normal weight at rest less than your normal weight at rest
less than your normal weight at rest
Is there gravity in space?
yes
Will Earth continue to orbit the sun?
yes, as long as nothing comes along to take angular momentum away
a change in momentum occurs when net force is not ______
zero