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Level 132

Universal Law of Gravitational Force


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all bodies of mass
exert a gravitational pull on other bodies of mass
small masses exert
less gravitational force
large masses exert
more gravitational force
gravitational force decreases
as distance between objects increases
gravitational force increases
as distance between objects decreases
increased mass and decreased distance
result in the greatest gravitational pull
planets and stars
gravity causes the formation of
in orbit
gravity holds all objects of the Solar System
Newton's first law
An object at rest remain and an object in motion remains in motion UNLESS it experiences an unbalanced force. Also called the Law of Inertia.
an object in motion will remain in motion
at a constant velocity, unless acted upon by unbalanced net force
but gravity from the star pulls on its mass
a planet in motion, would stay in motion at a constant velocity
the planet travels in free-fall around the star
if a star pulls on the mass of a planet
in a state of free-fall
all objects in orbit are actually
object in forward motion
with constant velocity and pull of gravity
free-fall around the sun
the combination of constant velocity and pull of gravity results in
but gravity from a planet pulls on its mass
a satellite in motion would maintain forward motion at a constant velocity
star
a planet orbits a
planet
a satellite orbits a
You have mass -->
Youre attracted to everything
inverse square law
a quantity varies with the inverse square of its distance from its source
Attraction depends on
Mass of objects
Strong nuclear force
Four forces of nature
Binds nucleus
Strong nuclear force
Electromagnetic force
Binds atoms into nucleus
Gravitational Force
(physics) the force of attraction between all masses in the universe
What did Newton know?
He did not know the constant G
(Each mass starts equal)
Double 1 mass --> double Fg
Effect of distance on Fg
Double distance --> 1/4 Fg
Henry Cavendish
A British physicist and chemist whose most famous experiment used a torsion bar to determine the value of the universal gravitation constant to determine the weight of the earth
How cavendish found G
Massed flask of mercury...
Longitudinal
A wave in which the vibration of the medium is parallel to, or in the same direction as, the direction in which the wave travels is called a _______
Medial
Through stomach pointing in back and front axis
Not a parabola
Centripetal force vs. radius graph
Transverse
Side to side axis
Lift from air under wings
Airplane banks and makes turn --> centripetal force supplied by
Mass doubled to 2g
Spinning in circular space station --> vt doubled from 1g of Force -->
AU
Astronomical unit
Tyho Brahe
Kepler took over his planetary studies with planetary motion
2nd Law
Acceleration is produced when a force acts on a mass
3rd Law
Every action has and opposite re-action
yes
do all objects emit radiation at any temperature (answer yes or no)
mass
a body of coherent matter, usually of indefinite shape and often of considerable size
Weight - measure of Fg
Quantity that may change with location
Newtons concept of inertia
Without outside force, moving objects continue at constant speed in straight line
force
(interactions between two objects)
Sideways
Tangential velocity that prevents moon from hitting earth
Siting still
Normal weight
Accelerating down
Less weight than usual
Accelerating up
Greater weight than usual
Free Falling
no other forces except gravity are acting on the object
False
(T/F) Tycho Brahe was a Danish astronomer who confirmed Copernicus's theories by making many observations with his telescope.
Rotational giant wheels produce
Artificial gravity --> space habitats in future
Perturbation
Deviation of and orbiting object from its path around center of force caused by another center of force
Earth satellite
Projectile moving fast enough to fall continually around earth
Ellipse
Satellite travels in an
Constant
Speed that does not vary
8 km/s
Speed object must have to orbit earth
No component of Fg along direction if alley
Why is a satellite and bowling ball not effected by gravity?
Segments of ellipses
Parabolic paths of projectiles
Crash into sun
Planet with tangential velocity of 0
Top of mountain, weight is
Less than at gerund level
Gravitational forces
Gravitational field interacts to cause
Field lines show
Direction and acceleration of force field
Earths center
Where is earths gravitational field zero
weight
A force that comes from gravity pulling down on any object with mass
What are the four fundamental forces?
gravitational force, electromagnetic force, strong nuclear force, weak nuclear force
sun on earth, earth on moon
What is an example of gravitational force?
2 ways an electric charge occurs
charged particles at rest or in motion exert electric forces on each other, charged particles in motion produces magnetic forces on each other
weak nuclear force
Force involved in radioactive decay
linear acceleration
An apple falling to the earth is what kind of acceleration?
earth, force
Since it fell to the Earth, the _ exerted a _ on the apple
exert an equal but opposite force on the Earth
Based on Newton's third law, if the earth exerts a force on an apple that is dropped, the apple must...
attractive
Newton concluded that there is a _ force between any two objects
centripetal acceleration
a = centripetal acceleration
it would leave it's orbit in a straight line path
If the moon did not feel an attraction to the earth, what would happen to it?
Yes, they are changing direction
Are objects that are moving in a circle and constantly changing direction accelerating? Why or why not?
Newton's Law of Universal Gravitation
Every particle in the universe attracts every other particle with a force that is directly proportional to the product of the masses and inversely proportional to the square of the distances between their centers
the earth
Since gravity is the weakest of all the 4 fundamental forces, we can only sense its efects when masses like that of _ are involved
no
Does an ideal gas actually exist...?
your weight
The force of attraction between you and the earth is equal to...?
inverse
Force is _ly proportional to the square of the distance
¼ as large
If the distance is doubled, what happens to the force?
1/9 as large
If the distance is tripled, what happens to the force?
the inverse square law
The relationship between force and distance is called...?
they are equal
On planets and other celestial bodies, what is the relationship between Fw and Fg?
g=(Gm2)/r^2
What is the derived formula for acceleration due to gravity?
Tycho Brahe
Johannes Kepler started his astronomy career as an assistant to _______.
Johannes Kepler
A german astronomer who created the three laws of planetary motion
Isaac Newton
A man from England who realized that the planets move around the Sun because of inertia as well as developing the laws of motion and gravity
What are Kepler's Three laws of Planetary Motion?
the paths of planets are ellipses with the center of the sun at one focus, an imaginary line from the sun to a planet sweeps out equal areas in equal amounts of time, rati…
fastest, slowest
Planets move _ when closest to the sun, they move _ when farther away
period
Time per second; time to go around once
What is speed?
Distance traveled divided by the time interval during the motion.
What is velocity?
The speed of an object in a particular direction.
By changing direction
How can an object have a constant speed and a changing velocity?
direction
A point toward something, determined by its orientation and sense.
How is speed calculated
total distance divided by total time
It is a triangle and it means change
what does the delta symbol look like and what does it mean
meters/second or km/hr
What are metric units for speed
what is acceleration
The rate at which velocity changes overtime
m/s squared
what are the metric units for acceleration
what is formula for acceleration
final velocity-starting velocity/time it takes to change velocity
what is a force
A push or a pull
Newton
(kg*m)/(s*s)
Causes a non-moving object to move
What does a net force cause an object to do
inertia
_______ is the property of an object that leads it to resist any change in motion
Define Newton's first law
An object at rest remains at rest and an object in motion remains in motion, in a straight line unless acted upon by an unbalanced force.
Define Friction
A force that opposed motion between two sources that are in contact
Energy of heat
Friction transforms energy of motion into energy of what?
Friction, intertia
To move an object, what forces must a person overcome?
Meters/second
How is speed measured
s=d/t
Speed equation
D=SxT
How do you solve for D in speed?
D/S
How do you solve for T in the equation for speed.
Mass times acceleration
What is the equation for force
Work/time
What is the equation for power?
Change in speed/time
What is the equation for acceleration?
M/s squaredMotion
What is the unit for acceleration?
displacement
A change in position (delta p).
Distance
a path taken and always a positive number
Newtons 1st law of motion (The law of Inertia)
An object at rest will stay at rest and an object in motion will stay in motion in a straight line at a constant speed (velocity) unless an unbalanced force acts upon it.
Force:
an action that has the ability to Change motion
Mass:
- The amount of matter of "stuff" that makes up an object.
Volume:
the measure of the amount of space an object takes up
Weight:
the force due to Gravity on an object
Law of Inertia
Newton's 1st Law is also know as the law of:
F=ma
Force Formula
action-reaction
other name for third law
note:
while most people know what newtons laws say many people do not know what they mean (or simply do not believe what they mean
Newtons Second Law
A law of motion that states that acceleration is equal to force divided by mass.
Newtons Third Law
A law of motion that states that for every action force here is a reaction force equal in strength and opposite in direction.
1st Law
An object at rest stays at rest, an object in motion stays in motion, UNLESS an UNBALANCED force acts upon it.
forces
Something that does work or causes a change
objects
they are stationary when forces are balanced
gravity
(physics) the force of attraction between all masses in the universe
unbalanced forces
forces that cause a change in the motion of an object
friction
a contact force; type of force between two touching surfaces
tension
a force exerted by any segment of a rope or string on an adjoining segment is _______.
support
lift, in the air (planes/birds)
buoyancy
the ability to float
1st type of friction
sliding friction, like ice skating
2nd type of friction
rolling friction, like bowling
3rd and 4th type of friction
Fluid friction (air of liquid) air and water resistance
lubrication
friction can be reduced by:
one newton is equal to:
the force required to accelerate one kilogram of mass at one meter/second/second
note
objects with different masses accelerate to the ground at the same rate, terminal velocity = 9.8 m/s/s
types of foces
gravity, electricity, magnetism, friction
action and reaction forces
are equal, in opposite directions, and happen at the same time
example of friction
when you rub your hands together in the winter and they get warmer
example of the third law
bat hits ball, ball hits bat
What is friction caused by?
-the random, microscopic irregularities of a surface
Kinetic Friction
Friction between moving surfaces
What is kinetic friction?
the friction encountered When surfaces slide against one another with a finit relative speed
the magnitude of the normal force (n)
What is the force of kinetic friction found to be proportional to?
fk = μk(N)
States mathematically, what can this observation be written as?
What is μk known as?
the coefficient of kinetic friction
-none, it is dimensionless
What dimensions does μk have?
is always positive
What are typical values for μk?
high friction
Are high μk values indicative of high friction or low friction?
oppose motion
Does the force of kinetic friction oppose or support motion?
Is fk = μk(N) a vector equation?
-no, because N is perpendicular to the direction of motion
What is the role of static friction?
to keep two surfaces from moving relative to each other
What is it due to?
the microscopic irregularities of surfaces that are in contact
stronger
The bigger an object, the _______ gravitational force it exerts.
Why?
because both person a and B cover the same angle in the same time
any value between zero and Fsmax
What values can the force of static friction have?
Fsmax is proportional to the magnitude of the normal force
What is the relationship between the normal force and the force of static friction?
Fsmax μs(n)
What is the equation that describes this relationship?
What is μs called?
the coefficient of static friction
-in most cases, μs is greater than μk
How do typical values for μs and μk compare?
What does this indicate?
that the force of static friction is greater than the force of kinetic friction
-between 0.01 and 4
What is the range of typical μs values?
What is the relationship between the force of static friction and the area of contact?
the force of static friction is independent of the area of contact between the surfaces
In what direction does the force of static friction work?
-parallel to the surface of contact, and in the direction that opposes relative motion
static friction
A car drives with its tires rolling freely. Is the friction between the tires and the road kinetic or static?
kinetic
Energy of motion
allow a car to stop with static friction rather than kinetic friction
What do antilock braking systems allow, in terms of static and kinetic friction?
braking distance is reduced
As a result, what is the impact on braking distance?
Due to what fact?
the fact that μs is typically greater than μk
What is the tension in a rope at points 1, 2, and 3?
-in the limit of a rope of zero mass, the tension is the same throughout the rope
-9.81
One scale holds a 1 kg weight from the ceiling. The other scale sits in between two strings (and pulleys), and holds a 1 kg weight on either side. The second scale measures the f…
the net force acting on it is zero
What does it mean when an object is said to be in "translational equilibrium"?
the acceleration is zero
From Newton's second law, what does this mean about the object's acceleration?
In two dimensional systems, what does translational equilibrium imply?
-two independent conditions, Fnet x = 0 and Fnet y = 0
-since the bucket is rising with constant speed, it has zero acceleration
Consider a person lifting a bucket of water from a well by pulling down on a rope that passes over a pulley. If the bucket's mass is m, and it is rising with constant s…
tension is less than the tension in the first case
A person hoists a bucket of water from a well and holds the rope, keeping the bucket at rest. A short time later, the person ties the rope to the bucket so that the …
the same
if take off and landing heights of a trajectory of a projectile are the same, then the time from ground to apex should be _______ the time from apex to ground
the tension in the string is less than M2g
Two masses, M1 and M2, are connected by a string that passes over a pulley. Mass M1 slides without friction on a horizontal tabletop, and mass M2 falls vertically downward. Both masses move with cons…
-g/-9.80
When two masses, M1 and M2, are connected by a string that passes over a pulley...what is the acceleration of M2 when M1 = 0?
0/zero!
The acceleration of M1 and M2 when M1 = M2
free fall
a state in which an object is gravitationally drawn to the earth's surface and is unaffected by any forces besides weight
less than
Is the force of gravity for M1 (M1g) greater or less than the force of tension in this instance?
greater than
Is the force of gravity for M2 (M2g) greater or less than the force of tension in this instance?
because #REF! is heavier than #REF!
What is M1g less than the force of tension while M2g is greater than the force of tension?
-Force of static friction will equal 10 N
If you are given N and a value of static friction that equals 5 N, what will be the impact on the force of static friction if N is doubled? (N becomes 2 N) (igno…
it will be twice as hard to move the object
What will the implications be then on how hard it will be to move the object?
Explain why it is impossible to hold up a street light with perfectly horizontal wires?
-neither of the wires has a vertical component, so there is nothing to balance out the gravitational force
What are the two "pulley tricks"?
tension in a freely running massless rope is uniform
What does this mean in terms of the tension?
-if you have two objects, the tension acting on the two objects is the same!
What does this mean in terms of acceleration?
acceleration of the two objects will be equal in magnitude but opposite in direction
size is constant
Describe the size of the force of kinetic friction?
-varies, from 0 to (ms)(N)
Describe the size of the force of static friction?
because it is a good measure of the contact between an object and a surface
Why is N used to calculate the force of static friction and the force of kinetic friction?
As a ratio, what does the coefficient of static friction represent?
the maximum amount of friction force that can be exerted per unit of contact force
how smooth a surface is
What does the coefficient of static friction give you a good gauge of?
Explain why mass has no impact on the force of static friction or kinetic friction
-although having a greater mass means that there is a larger force trying to move an object (mg sin theta), there is also a larger force trying to hold it in place (mg cos theta, N)
Why not?
because each different conservative force has a different expression for potential energy
mg sin theta > force of static friction max
When an object is on an incline and it slides, what is the relationship between mg sin theta and force of static friction max?
the force needed to start a motion is greater than the force needed to maintain a motion
How does the force needed to start a motion compare to the force needed to maintain a motion?
force of static friction max > force of kinetic friction
What does this then imply about the relationship between the force of static friction max and the force of kinetic friction?
the static coefficient is always greater than the kinetic coefficient for the same two surfaces
What does this then imply about the static coefficient and the kinetic coefficient for the same two surfaces?
force of push < force of static friction max
When an object stays at rest, what is the relationship between the force of the push and the force of static friction max?
velocity will not be constant because the object will continually be accelerating
When an object moves, will its velocity be constant? Why or why not?
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Energy, Work, Power