chapter 4 ps
if a projectile is fired straight up at a speed of 10 m/s, neglecting air resistance, the time it takes to reach the top of its path its
1 sec
a woman who normally weights 400 N stands on top of a very tall ladder so she is one earth radius above Earth's surface. What is her weight there?
100 N
a gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. neglecting air resistance, how far downrange will the bullet be 1 s later?
100 m
if a projectile is fired straight up at a speed of 10 m/s, neglecting air resistance, the total time to return to its starting position is
2 sec
if there were no gravity, a ball thrown upward at an angle would follow a straight line path. due to gravity, however, at the end of 2 s it is
20 m below the straight line
a softball player determines her pitching speed by throwing a ball horizontally from an elevation of 5 m above the ground. The ball lands 20 m downrange. what is her pitching speed
20 m/s
ignoring air resistance, what maximum speed can be given to a horizontally moving tennis ball as it clears the net 1.25 m high to remain with in the edge of the court, which is 12.0 m from the bottom of the net
24.0 m/s
a softball player determines her pitching speed by throwing a ball horizontally from an elevation of 20 m above the ground. the ball lands 50 m downrange what is her pitching speed
25 m/s
2 projectiles are fired at equal speeds but different angles. one is fired at an angle of 30 degrees and the other at 60 degrees. with no air resistance, the projectile to hit the ground first will be the one fired at
30 degrees
with no air resistance , a projectile fired at 60 degrees had the same range as if it were fired at
30 degrees
Consider 2 planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them doesn't change, then the force between them is
4 times as much
with no air resistance, a projectile fired at 50 degrees has the same range as if it were fired at
40 degrees
a ball is thrown horizontally from the top of a tall cliff. 3 s later, the ball has fallen a vertical distance of
45 m
a stone is thrown horizontally from the top of the cliff. one second after your hand it drops a vertical distance of
5 m
if there were no gravity, a ball thrown upward at an angle would follow a straight line path. due to gravity , however, at the end of 1 s it is
5 m below the straight line
a rock is thrown upward at 50 m/s. neglecting air resistance its speed Upton returning to its starting point is
50 m/s
Phil stands at rest with both feet on a scale that reads 500 N. after he gently lifts on foot, the scale reads
500 N
what is the force of gravity on a 500 N woman standing on Earth's surface
500 N
a projectile is launched at an angle of 15 degrees above the horizontal and lands downrange. with no air resistance, what other projection angle for the same speed would produce the same downrange distance?
75 degrees
an object is places exactly halfway between the Earth and the Moon. The object will fall toward the
Earth
an airplane flies at 40 m/s at an altitude of 50 m. the pilot drops a heavy package that falls to the ground below. neglecting air resistance, the package will land
beneath the plane
a very massive object A and a less massive object B move toward each other under the influence of gravity. which force, if either, is greater
both forces on each other are the same
a ball rolls off the edge of a table at the same time another ball drops vertically from the same table. the ball to hit the floor first is the
both hit at the same time
a hunter fires a bullet from a horizontally held rifle while simultaneously dropping another bullet from the side of the rifle. the bullet to hit the ground first is
both hit at the same time
as a bowling ball that rolls off the edge of a table falls, its horizontal component of motion
remains constant
weight can be simulated in a space vehicle if the vehicle is
rotating
A supplier wants to make a profit by buying gold by weight at one altitude and selling it at the same price per newton at another altitude. the supplier should
buy at a high altitude and sell at a low altitude
if the radius of earth somehow increased with no change in mass, your weight would
decrease
if Earth's mass somehow decreases with no change in its radius, you weight would
decrease also
If earth's mass decreases to one half its original mass with no change in radius, your weight would
decrease to 1/2
A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its vertical component of velocity
decreases
when the distance between a pair of stars doubles, the force between them
decreases by 1/4
an object is places exactly halfway between the Earth and the Moon. the object will fall toward the
earth
your weight is equal to mg when you are
firmly supported on a horizontal surface and in equilibrium
how far away from the earth must one travel to completely be beyond earth's gravity
forget it; you can't travel far enough
an earth satellite is simply a projectile
freely falling around the earth
the sun is spherical due to
gravitation
according to Newton, the closer gravitational interacting objects are to each other, the more the
gravitational force between them
according to newton, the greater the masses of interacting objects, the
greater the gravitational force between them
If the masses of 2 planets doubles and the distance between them also doubles, the force between them would be
half as much
if the radius of the Earth somehow decreases with no change in mass, your weight would
increase
2 objects move toward each other due to gravity. As the objects get closer and closer, the force between them
increases
2 objects move toward each other due to gravity. as the objects get closer and closer, the acceleration of each
increases
as a bowling ball that rolls of the edge of a table falls, its vertical component of motion
increases
when the distance between a pair of stars decreases by half, the force between them
increases to 4 times as much
perturbations of planets are due to
interplanetary forces
neglecting air resistance, after a ball leaves your hand when you toss it upward, the force on it
is only the force due to gravity, always directed downward
the moon continually falls toward earth, but doesn't get closer because
its tangential velocity causes it to fall around as well as toward the earth
one second after a ball rolls of the edge of a horizontal surface at a speed on 10 m/s,
its vertical component of velocity is 10 m/s , its speed is about 14 m/s
according to Newton, the greater the distance between gravitationally interacting objects, the
less the gravitational force between them
you can experience weight
standing on earths surface, in an upward accelerating elevator, in a rotating habitat in space
the universal law of gravity
that gravity is universal
this chapter states a link between newtons universal law of gravity and
the US constitution
occupants of the international space station experience weightlessness due to
the absence of a support force
a hunter aims a rifle at an angle of 10 degrees above the horizontal. the hunter fires a bullet while simultaneously dropping another bullet from the side of the rifle. the bullet to hit the ground first is
the fired one
planets wobble in their orbits due to
the gravitational attraction to other planets
the moon does not crash into earth because
the moon has a sufficient tangential speed
after a stone that is thrown straight up reaches the top of its path and then falls downward, its acceleration
the same as the top of its path
nellie tosses a ball upward at an angle. assuming no air resistance, which component of velocity changes with time
the vertical component
planets would crash into the sun if it weren't for
their tangential velocities
Consider 2 planets in space that gravitationally attract each other. If the masses of one planet is doubled, and the distance between them doesn't change, then the force between them is
twice as much
the identities of dark energy and dark matter are
unknown at this time. subjects of intense astronomical interest.
Dwarf planet Pluto was discovered by perturbations of
uranus and neptune
Compared to other fundamental forces, the Universal Gravitational Constant G indicates gravity to be a relatively
weak force
inside a freely falling elevator you would have no
weight
inside a freely falling elevator your
weight is zero
strictly speaking, when you step off a curb you are momentarily
weightless
an airplane flying overhead drops a care package directly over mike at rest in his corvette. neglecting air resistance, the package will land
well ahead of mike and his corvette
passengers in a highly flying jumbo jet feel their normal weight in flight, whereas passengers in an orbiting space vehicle do not because they are
without supporting forces
your weight it defined to be the force
you exert against a supporting force
2 motorcycle stunt drivers, one light and the other much heavier, ride their motorcycles up and off an inclined ramp at identical speeds. they both rise in the air and land downrange. neglecting air resistance , the one to attain the greatest height and greatest range is the
light and heavy driver are the same
an object is thrown vertically into the air. Because of air resistance, the time for its descent will be
longer than the ascent time
for the astronauts inside an orbiting space vehicle the force of gravity that acts on them is
mainly due to earth below
each of us weighs slightly less inside the ground floor of a skyscraper than we do on the ground away from the skyscraper because the
mass of the building attracts us upward slightly
why doesn't the moon fall toward the Earth like apples do?
moon does fall but due to its tangential motion it also falls around the earth
if there were no gravity, a cannonball fired upward at 45 degrees would follow a straight line path. due to gravity, however, at the end of 3 s it is
more than 20 m below the straight-line
as some point between Earth and the Moon, the forces due to gravity on a space traveler would be the same when this point is
nearer to the Moon
the amount of gravitational force that acts on a space vehicle that orbits Earth is
nearly as much as the vehicle's weight on Earth's surface
wobbles in the path of Uranus led to the discover of
neptune
With no air resistance a projectile fired horizontally maintains its horizontal component of velocity because
no horizontal force acts on it
if the masses of 2 planets doubles and the distance between them reduces by half, the force between them would be
none of the above
what holds earth satellites up so they don't crash into earth
nothing, they continually fall fast enough around the earth not to crash
the tangential velocity of an earth satellite is its velocity
parallel to the surface of earth
the force of gravity on a bowling ball rolling along a horizontal surface doesn't change its speed because the force is
perpendicular to its direction of motion
the radial velocity of an earth satellite is its velocity
perpendicular to the surface of earth
an outcome of universal gravitation is that
planets aren't cubes with sharp corners, its discovery prompted other laws of nature , it provided prediction and discovery of planets
the force of gravity acts on all apples on an apple tree. some apples are twice as far from the ground. such twice as high apples of the same mass, have
practically the same weight
air resistance on a high speed projectile shortens its
range and maximum height
You experience weightlessness
- in the absence of a supporting surface. - in a freely falling elevator. - momentarily when you step off a chair.
if the sun were twice as massive
-its pull on the Earth would double -Earth's pull on the Sun would double
a bulled fired horizontally hit the ground in .5 s. if it had been fired twice the velocity it would have hit the ground in
.5 sec
the universal constant G was first measured by
Cavendish
the planet Jupiter is about 300 times as massive as earth, yet on its surface you would weigh only about 3 times as much because
Jupiters radius is 10 times Earth's radius
a dropped ball gains speed because
a gravitational force acts on it
the hang time of an athlete who moves horizontally 2.0 m during a l.25 m high jump is
about 1 s
without air resistance, a projectile fired horizontally at 8 km/s from a mountain top will
accelerate downward at g as it moves horizontally
If earth's mass somehow doubles with no change in its size, and your mass stays the same, your weight
also doubles
If your mass doubles, your weight
also doubles
a bullet fired from a rifle begins to fall
as soon as it leaves the barrel
in the vacuum of outer space far from the sun, there is no
atmospheric pressure