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