Chapter 4 Flashcards
Velocity
Speed and Direction
Acceleration
Any change in velocity
How do we describe motion?
Speed: Rate at which object moves
Speed
distance/time
Gravity (meters/ seconds squared)
9.8 m/s^2
Momentum
mass x velocity
All falling objects (disregarding weight)
fall at the same rate
Higher velocity means…
higher momentum
Net force changes…
momentum (meaning an acceleration)
Angular Momentum
the rotational momentum of a spinning (orbiting) object
Gravitational force
Relativity
Mass
amount of matter in an object
Weight
force that acts upon an object
When are you weightless?
in a free-fall.
On the moon, what is less? which stays the same?
your weight is less
your mass is the same
why are astronauts weightless in space?
there is gravity in space,
weightlessness is is due to..
constant state of free fall.
Newtons first law of motion?
- an object in motion will remain in motion, unless a net forces acts on it
- Law of inertia (Voyager Spacecraft)
Newtons second law of motion?
F = mass x accerelation
Newtons third law of motion?
for every action there is a equal and opposite force
action and reaction
is the force that earth exerts on you larger, smaller, or the same as the force you exert on it?
Earth and you exert equal and opposite forces on each other
angular momentum =
mass x velocity x radius
angular momentum
keeps the planet orbiting the sun
angular momentum of an object
- unless an external twisting force is acting on it
- earths rotation and orbit will continue indefinitely
Angular momentum conservation
why objects rotate faster when they shrink in radius
-ex. collapse of stars
kinetic
motion
radioactive
light
energy can change
but cannot be destroyed
thermal energy
collective kinetic energy of many particles
temperature
average kinetic energy of the many particles in a subject
0 degree kelvin
no motion
Gravitational potential energy depends on..
- objects mass
- strength of gravity
- the distance an object could potentially fall
at the highest point
more gravitational potential energy and less kinetic energy
Mass energy
mass itself is a form of energy
E =
- 90 million
- mc^2
Conservation of energy
- energy can neither be created nor destroyed
- it can change from or be exchanged between objects
-total energy content was determined in big bang
what determines the strength of gravity?
Universal law of gravitational
1st universal law of gravitation
every mass attracts other other mass
2nd universal law of gravitation
attraction is directly proportional to the product of their masses
3rd universal law of gravitation
attraction is inversely proportional to the square of the distance between their centers
Fg =
G (m1m2)/D^2
How does Newtons law of gravity extend Keplers law?
- Kepler’s first law applies to all objects, not just planets
- ellipses are not only orbital paths
Newton generalized kepler’s 3rd law
then you calculate mass of the larger object
- we could calculate mass of something if we know something that orbits it.
- like we could measure Jupiter’s mass from orbital period and distance of one of its moons.
Slower…
less kinetic energy
Escape Velocity
- 2 km
- could travel into the solar system
escape and orbital velocities
do not depend on mass
How does gravity use tides?
difference in the moon’s gravitational pull stretches earth.
-moons pull harder on near side of earth than on far side
Hubble space telescope speed?
8km per second (international space station)
spring tides
- strong tides (full and new moon)
- maximum every 6 hours
neep tides
-tides not so extreme (3rd quarter & 1st quarter moon)
moon effects are how many more times stronger than the sun?
2
Tidal Friction
gradually slows Earth’s rotation (makes moon further from earth)
Size of tides depend on
phase of the moon
