PHYSICS Final - Semester 1
The accelerations possible for a ball on an incline plane range from
0 to g
A 10-kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is(a=f/m)
1 m/s^2
A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is
1 m/s^2
gravity on the moon
1.6 m/s²
A certain jack has a theoretical mechanical advantage of 500. However, due to frictional forces, the actual mechanical advantage is only 100. What is the efficiency of the jack?
1/5
How do you find Newtons(what do you multiply mass by)?
10
An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about
10 m/s
What is the distance fallen for a freely falling object from a rest position 6s after?
180m
How do you find pounds(what do you multiply mass by)?
2.2
A hydraulic lift used at an automobile repair shop raises a 1000kg car two meters off the ground. What is the potential energy given to the car?(10,000(2))
20,000J
A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car?
2000 N
What is the distance fallen for a freely falling object from a rest position 2s after?
20m
An astronaut of mass 70kg weighs 700N on Earth's surface. His weight on the surface of Mars where the acceleration due to gravity is 3.7 m/s^2 would be about(hint:70kg*3.7m/s^2=mg)
260N
Newton's 2nd Law of Motion
A=F/m
The first scientist to be credited for postulating that Earth circled the Sun was
Copernicus
Newton's Second Law
F=ma
impulse
Ft
Predict how the vertical component of the velocity will change with time after the projectile is fired
It first decreases to zero and then increases in the opposite direction
Newton viewed the curving of the path of a planet as being caused by a force acting on the planet. How did Einstein view the curved path of a planet?
Moving in curved 4-dimensional spacetime
What was the cause of perturbations discovered in the orbit of the planet Uranus? What later discovery did this lead to?
Neptune caused the perturbations, and later Pluto was discovered
who envisioned the motion of planets as projectiles obeying the laws of physics?
Newton
What law refined the concept of inertia?
Newton's First Law
A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls?
Rising or falling, it does not change
if a ball is thrown horizontally and another is thrown down, which will have the greater speed upon impact?
The ball thrown horizontally
Why is a black hole invisible?
The escape velocity of the black hole is greater than the speed of light
Why doesn't the force of gravity change the speed of a bowling ball as it rolls along a bowling lane?
The force is at a right angle to the motion
Why doesn't the force of gravity change the speed of a satellite in circular orbit?
The force is at a right angle to the velocity
What was the direction of the force on a planet in a circular orbit in Kepler's thinking? In Newton's thinking?
The force was parallel to the motion for Kepler, whereas the force was toward the planet for Newton.
For orbits of greater altitude, is the period longer or shorter? Is the speed faster or slower?
The period is longer and the speed is slower
What did Kepler discover about the periods of planets and their distances from the Sun?
The period squared was proportional to the distance cubed
mechanical equilibrium
The state of an object or system of objects for which there are no changes in motion
A roller coaster is initially pulled up by a hill from Point A, where it has no potential energy, to Point B. It then rolls down a hill, around the loop at points C and D, and comes to rest at Point E(Points A, C, and E are all the same level). Since the car starts out at rest at Point A and ends up at rest at Point E
The work done initially pulling the car up the hill is eventually completely conserved into heat energy
What is the magnitude of the gravitational field at Earth's center?
What is the magnitude of the gravitational field at Earth's center?
Which has greater mass? a)an automobile battery b)a king size pillow
a
static friction
a friction force that acts on objects that are not moving
inelastic collision
a type of collision in which the kinetic energy after the collision is less than the kinetic energy before the collision
If an apple experiences a constant net force, it will have a constant
acceleration
You double the net force on an object, you'll double its
acceleration
a constant net force on a railroad car produces constant
acceleration
A feather and a coin dropped in a vacuum fall with equal
accelerations
Earth pulls on the Moon and the Moon pulls on the Earth. This is an example of a
action-reaction pair
when you stand at rest on a pair of bathroom scales they
add up to your weight
you're at rest in a hammock when I'm hungry mosquito season opportunity for lunch. A mild 2 m/s breeze is blowing. If the mosquito joins you for lunch in hover over by flying
against the breeze at 2 m/s
When a skateboarder pushes on the wall a)the wall pushes on the skateboarder b)such a push couldn't happen unless the wall pushed on the skateboarder c)an interaction occurs between the skateboarder and the wall
all of the above
Which of these vary for satellites in elliptical orbits? speed, momentum, or kinetic energy
all of the above
You experience weightlessness a)in a freely falling elevator b)momentarily when you step off a chair c)in the absence of a supporting surface
all of the above
Action and reaction pairs of forces
always act simultaneously
The force with which Earth pulls on the Moon is
an equal force to the force that Moon pulls on the Earth
Earth moves about 30 km/s relative to the Sun. When you jump upward in front of a wall, the wall doesn't slam into you at 30 km/s. This is because the wall
and you are moving at the same horizontal speed before, during, and after your jump
The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance. a)after the target b)before c)above
b
Angular momentum is conserved for a satellite in an a) elliptical orbit b)circular orbit
both
Caitlin runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is a) 5m/s b) 11 m/s
both
Is the sum of kinetic and potential energies a constant for satellites in circular orbits, in elliptical orbits, or in both?
both
You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?
both the same
Arnold strongman and Susie small each pole very hard on opposite ends of a rope in a tug-of-war. The greater force on the rope is exerted by(3rd law)
both the same interestingly
A Mack truck and a Volkswagen traveling at the same speed collide head-on. The a) impact force is greater on b)the vehicle to undergo the greatest change in velocity is
both the same, Volkswagen
A rocket becomes progressively easier to accelerate as it travels upward from the ground mainly because a) gravity becomes weaker with increased distance b) the applied force on the rocket increases as burning of fuel progresses c) the mass of the rocket decreases as fuel is burned
c
An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will a)move in the opposite direction at 20 m/s b)move in the opposite direction at a higher speed c)move in the opposite direction at a lower speed
c
When you rub your hands together, you
cannot push harder on one hand than the other
acceleration
change in velocity(vf-vi)/time
The kinetic energy of a satellite remains constant when the satellite follows a __________.
circular path
Black holes are essentially ______
collapsed stars
m1v1 + m2v2 = (m1+m2)v
conservation of momentum
Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to
continue moving at 40 km/h
The normal force that acts on a block of ice that slides on a ramp
decreases as the slope of the ramp increases
The emphasis of the orange-and-apple sequence in your textbook is
defining systems
A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
directed downward
the difference between speed and velocity involves
direction
Distance and direction of an object's change in position from the starting point
displacement
speed
distance/time
Einstein's theory of gravitation, compared with Newton's, _______.
eliminates the role of force
Kepler was the first to be credited for discovering that planets follow __________
elliptical paths
due to inertia, perhaps a railroad train in motion should continue moving indefinitely when is engine is turned off. This is not observed because railroad tracks
encounter opposing forces (friction etc)
If two forces act on the same object, they form an action reaction pair
false
More power is needed to carry a heavy suitcase slowly up a flight of stairs than to carry the suitcase quickly up the same flight of stairs
false
Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to
follow a straight-line path
the resistive force that opposed the motion or attempted motion of an object either past another object with which is is in contact or through a fluid
friction
Which of the following is NOT an example of a simple machine? Fulcrum, Pulley, Lever. Inclined plane
fulcrum
A high diver steps off a diving platform that is 10 meters above the water. If no air resistance is present, during the fall there will be a decrease in the diver's
gravitational potential energy
mgh
gravitational potential energy
A pair of equal-length vectors at right angles to each other have a resultant. If the angle between the vectors is less than 90 degrees, their resultant is
greater
When Joshua brakes his speeding bicycle to a stop, kinetic energy is transformed to
heat
when you quickly jerk a cart foward that has a ball resting in the middle, the ball
hits the back of the cart
Ft=∆mv
impulse-momentum relationship
The direction of a gravitational field is
in the same direction as gravitational attraction
.What are two ways to increase impulse?
increase the force or increase the time the force is applied
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
The horizontal and vertical components of velocity for a projectile are __________
independent of each other
if something is moving at a constant velocity
inside the objects act as if no force is acting on it
The speedometer of an automobile reads
instantaneous speed
If the net force on a cart is triples, the cart's acceleration
is tripled
Whenever the net force on an object is zero, its acceleration
is zero
Galileo taught us that if you roll a ball along a level surface it will
keep rolling if friction is absent
SI unit for mass
kilogram (kg)
1/2mv^2
kinetic energy
A 10 unit vector at 60 degrees from the vertical has a component with a magnitude
less than 10 units
A projectile is launched vertically upward at 50 m/s. If air resistance does affect motion then its speed upon returning to its starting point is
less than 50 m/s
A heavy bird sits on a clothesline. Will the tension in the clothesline be greater if the line sags a lot or if it sags a little?
little
If the Moon were four times as massive but twice as far from Earth, high tides on Earth would be
lower
the quantity of matter in an object, or its measure of inertia
mass
In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the a)moon b)earth c)jupiter
moon
Why is a force that is applied for a short time more effective in karate?
more force
When Nellie hangs suspended from a pair of ropes that are not vertical, the tension in each rope is
more than half her weight
A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that initially at rest and free to move. The bowling ball is set in motion with a momentum of
more than one unit
Why is it advantageous to roll with the punch in boxing?
more timer the same force
If a monkey floating in outer space throws his hat away, the hat and the monkey will both
move away from each other, but at different speeds
What class of motion, natural or violent, did Aristotle attribute to motion of the Moon?
natural
Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Neglecting air resistance, which ball hits the ground below with the greater speed?
neither, both hit with the same speed
To produce an acceleration to a system there must be a
net force on the system
Does friction vary with speed?
no
what essentially is the point of a vacuum?
no air resistance
if you carefully stand on your tiptoes on a weighing scale, your weight is
no different
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding is
no force needed
A ball rolled along a horizontal surface maintains a constant speed because
no horizontal force acts on it
The amount of work done on a heavy box carried by Nellie across a room at constant speed is
none
A river 100m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water leaves the West Bank. To land at a point due east of its starting point, must be pointed
nowhere(it can't be done)
N=0 applies to
objects in motion going in a uniform direction and objects at rest
fluid friction
occurs when a solid object moves through a fluid or gas
momentum
p=mv
Acceleration is greater for a satellite when it is at the _______
perigee
inertia is defined as a
property of matter
The exhaust product from a hydrogen fuel cell is
pure water
Once the crate is sliding, how hard do you push to keep it moving at constant velocity?
push with a force equal to and opposite the friction force
When you walk, you push on the floor to the left and the floor
pushes you to the right
scalar quantity
quantity with magnitude
vector quantity
quantity with magnitude and direction
When a star collapses to form a black hold, its mass
remains the same
The force exerted on the tires of a car that directly accelerate it along a road is exerted by the
road
a bicycle that travels four times as fast as another when braking to a stop will skid
sixteen times as far
A fast-moving missile soaring overhead possesses
speed
Kinetic energy is the energy an object has because of its
speed
Galileo found that the distance a uniformly accelerating object travels is proportional to the (hint:law of odd numbers, successions of odd numbers per unit of time)
square of the time
Which is normally greater: static friction or sliding friction on the same object?
static(takes more force to get an object moving/stopping than keep it sliding)
what did Galileo discover about the amount of speed a ball gained after each second when rolling down an inclined plane? what did he say about the balls acceleration?
the ball had constant acceleration so it gained the same speed every second
terminal velocity
the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity
Your weight as measured on your bathroom scale is
the force due to gravity on you
No work is done by gravity on a bowling ball that rolls along a bowling alley because
the force on the ball is perpendicular
A player hits a ball with a bat. If action is the force of the bat against the ball, reaction is
the force that the ball exerts on the bat
Your weight is
the gravitational attraction force between you and the Earth
Compared to the mass of a certain object on Earth, the mass of the same object on the moon is
the same
Compared to their weights (Burl and Paul) plus the weight of the scaffold, the sum of the tensions is
the same
inertia
the tendency of an object to resist a change in its motion
If you do work on a skateboard loaded with friends in one-third the usual time, you expend
three times the usual power
Tidal forces in general are the result of
unequal forces acting on different parts of a body
What Newton discovered most about gravity is that it is _______
universal
you cannot exert a force on a wall
unless the wall simultaneously exerts the same amount of force on you
The equilibrium rule applies to
vector quantities(force etc)
average speed
vi+vf/2
the amount of space an object takes up
volume
scalar quantities
volume, mass, and area
free fall
when the only force acting on an object is gravity
Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are
without support forces
1/2mv^2=Fd
work energy theorem
power
work/time
Does fluid friction vary with speed?
yes, both increase together
As you increase your push, does friction increase as well?
yes, until it reaches its maximum value
The force acting on an insect falling downward is
zero
What is the distance fallen for a freely falling object from a rest position 5s after?
125m
A girl pushes a cart to the left with a 100-N force. A boy pushes it to the right with a 50-N force. The net force exerted by the girl and the boy is
50 N to the left
Three object move at 1 m/s. A 4kg mass to the left, a 4kg mass to the left, and a 2kg mass up. What is the total kinetic energy of the system
5J(2+2+1)
A vertical vector of 3 units combined with a horizontal vector of 4 units makes a resultant of
5N
What is the distance fallen for a freely falling object from a rest position 4s after?
80m
force
a push or pull exerted on an object
An outcome of universal gravitation is that a)planets aren't cubes with sharp corners b)prediction and discovery of planets c)its discovery prompted other laws of nature
all of the above
Gm1m2/r^2
force of gravity
why doesn't a heavy object accelerate more than a light object when both are free falling?
greater mass cancels the greater force
after a rock is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)
the same as the top of its path
A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is
the same for both
A girl can easily lift a 80N rock with the help of a lever. When she pushes down with a 10N force, she lifts the rock .1m. How far does she move her arms to do this?
.8m
Max (15 kg) and Maya (12 kg) are ice-skating on a frozen pond. When Max is standing on the shore, he throws a 1.5-kg snowball at Maya, who is standing at the center of the pond. Maya catches the snowball and she and the snowball move away from the shore at 2.0 m/s. How fast was the snowball moving right before Maya caught it?(1.5kg * V = (1.5 + 12)kg * 2m/s)
18 m/s
A pot that falls from a ledge and hits the ground 45 m below hits the ground at
30 m/s
neglecting air resistance, how fast must you toss a ball straight up an order for it to take six seconds to return to its initial level?
30 m/s
A piece of rope is pulled by two people in a tug of war. Each exerts a 400N force. What is the tension in the rope?
400N
Which projectile spends more time in the air, the one fired from 30 degrees or the one fired from 60 degrees?
60
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much a)inertia b)mass c)volume
all of the above
A firecracker bursts while freely falling. The combined momentum of its fragments
equal the momentum of the firecracker at the time of burst
If your automobile runs out of fuel while driving, the engine stops. You don't come to an abrupt stop due to
inertia
When you flick a card from beneath a coin that hardly moves, you're illustrating
inertia
A fan attaches to an ice sail craft stalled on a windless day blows air into the sail the bounces backward upon impact. The boat
moves in the direction of the wind impact force
sliding friction
occurs when two solid surfaces slide over each other
When a tennis racket hits a ball,
the ball hits the racket
After rolling halfway down an incline, a marble's kinetic energy is
the same as its potential energy
The rate at which work is done is called power.
true
total time for an object in the air, going up and down
hang time
work
force x distance
As soon as a bowling ball rolls off the edge of a table its horizontal component of velocity
remains constant
Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide, stick, and moves at(hint:(2m-m=2mv)
1/2 m/s
distance traveled
1/2gt^2(average velocity x time)
neglecting air resistance, a bullet fired straight down from the top of a high cliff has an acceleration of
10 m/s^2
A river 100 m wide flows due south at 1 m/s. A boat that travels 1 m/s relative to the water pointed due east as it crosses from the west bank. The boat reaches the east bank
100m farther south(141m)
The force of friction on a sliding object is 10N. The force applied needed to maintain a constant velocity is
10N
Escape speed from Earth is any speed equal to or greater than __________.
11.2 km/s
A 300kg bear grasping a vertical tree slides down at a constant velocity. The friction force between the tree and the bear is
3000N
if a rocket initially at rustic star it's at a rate of 50 m/s^2 for one minute, it's speed will be
3000m/s(50*60)
Joshua is attracted toward Earth by a 500-N gravitational force. The Earth is attracted toward Joshua with a force of
500N
A 10-kg block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about(hint: A=0-10/2=5)
50N
The change in momentum that occurs when a 1kg ball traveling at 4 m/s strikes a wall and bounces back at 2m/s is
6 kg m/s
A 5,000 kg freight car collides with a 10,000 kg freight car at rest. They couple upon collision and move at 2 m/s. What was the initial speed of the 5000 kg car?(hint:5000v+0=30,000)
6 m/s
A projectile is launched at 30° above ground level. What other angle at the same speed will result in the same range?
60
Two projections are fired from ground level at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60. Neglecting air resistance, the projectile to hit the ground first will be the projectile with the angle of
60 degrees
A projectile is fired horizontally with an initial velocity of 300 m/s from a 20 m high tower.
600 m
An arrow in a bow has 70 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot?
70J
A projectile is launched from ground level at 15 degrees above the horizontal and lands downrange. What other projection angle for the same speed would produce the same down-range distance?
75
A 2.5kg brick falls to the ground from a 3m high roof. What is the approximate kinetic energy before it touches the ground?(hint:PE=KE)
75J
What is the speed needed for a projectile to orbit Earth? Why is it important that the projectile in the preceding question be 100 km or higher above Earth?
8 km/h, to avoid air resistance
A 2 kilogram mass is moving with a speed of 3 m/s. What is the kinetic energy of the mass?(KE:1/2mv^2)
9J
A bowl starting from rest at the top of an inclined plane accelerates at 2 m/s and reaches the bottom of the plane in three seconds what is the length of the plane?(hint:d=1/2at^2
9m
What exactly is a projectile?
An object that is projected by some means and continues in motion by its own inertia
A roller coaster is initially pulled up by a hill from Point A, where it has no potential energy, to Point B. It then rolls down a hill, around the loop at points C and D, and comes to rest at Point E(Points A, C, and E are all the same level). At which point does the car have both kinetic and potential energy?
D
6.67*10^-11 N*m²/kg²
G
When air resistance is neglected, why does the vertical component of velocity for a projectile change with time, whereas the horizontal component of velocity doesn't change?
Gravity is a purely vertical force
What happens to the strength of the gravitational field at the surface of a star that shrinks?
It increases
What is a gravitational field, and how can its strength be measured?
It is a force field on any body with mass. Its strength is the force per unit mass on a test mass
If Earth shrank, but there was no change in its mass, then what would happen to your weight at the surface?
It would increase
Why is kinetic energy a constant for a satellite in a circular orbit but not for a satellite in an elliptical orbit?
The force of gravity is perpendicular to the motion in a circular orbit but not in an elliptical orbit
A karate expert executes a swift blow and splits a cement block with her bare hand. The magnitude of the force on her hand is
The same as the force applied to the block
A package falls of a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is
about 30 m/s
As a pendulum swings back and forth a)its energy is all kinetic at the lowest part of the swing b)potential energy is transformed into kinetic energy c)its energy is all potential at the end points of its swing
all of the above
The earliest and most influential Greek philosopher was Aristotle, who among contributions thought that a)the four elements are earth, water, air, and fire b)violent motion requires a sustained push or pull c)all motion is either natural or violent
all of the above
Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom
at the same time as the light block
Nellie tosses a ball upward at an angle. Neglecting air resistance, the component of the initial velocity
decreases with time to reach the top
For every action force, there must be an equal and opposite reaction force that is
equal and opposite
The force that accelerates a rocket in outer space is exerted on the rocket by the
exhaust gases
A karate chop is more effective is one's hand a)bounces upon impact b)extends the time upon impact c)follows through upon impact
follows through upon impact
A hockey puck sliding at a constant velocity is
in equilibrium
If the speed of a bicycle is reduced to half before skidding to a stop, it will skid
one-fourth as a far
For an Earth satellite in circular orbit, list all the values that do not change: speed, gravitational force, and distance from the Sun and Earth
only speed, gravitational force, and distance from Earth
Neglecting air resistance, once a tossed ball leaves your hand
only the force due to gravity acts on it
The paths of fragments of fireworks are
parabolas
Compared with falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the
stopping time is longer on the carpet
When no forces act on moving objects their paths are normally
straight lines
natural motion (Aristotle) proceeds from the nature of an object, with a combination of the four elements
straight up or straight down
Is inertia the reason for moving objects maintaining motion or the name given to this property?
the name given to the property
If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity
the object eventually stops
a hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another Buller from the level of the rifle. Which bullet will hit the ground first?
the one dropped
apogee
the point in an orbit most distant from the body being orbited; the highest point
An automobile and a golf cart traveling at the same speed collide head on. The impact force is
the same for both
Two identical arrows, one with twice the kinetic energy of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates
twice as far
If you lift one load up two stories, how much work do you do compared to lifting one load up only one story?
twice as much
As you read this in your chair, how fast are you moving relative to the chair?
you are not moving relative to the chair but moving 100,000 km/h relative to the Sun
an object covers a distance of 8 m in the first second of travel, another 8 m during the next second, and 8 m again during the third second. It's acceleration is
zero
two students engaged in a tug of war each pull a rope in opposite direction with a force of 400 N. the net force on the rope is
zero and the root tension is 400N
Nellie pulls with a force of 50 N on a horizontal rope tied to a tree at rest. The net force on the rope is zero and the rope tension is
zero in the rope tension is 50 N
The muzzle velocity of a bullet fired from a rifle is 100 m/s neglecting air resistance at the end of one second a bullet fired straight up into the air will have traveled a distance of
(100-5)m/s
an apple weighs 1-N. When the apple is held at rest above your head, the net force on the apple is
0(at rest)
The vertical height attained by a basketball player who achieves a hang time of a full one second is about
1.25m
starting from rest, the distance a free falling object will have in half a second is about
1.25m
What is the ratio of escape speed from Earth to circular orbital speed? Ignore air resistance
1.41
Max (15 kg) and Maya (12 kg) are ice-skating on a frozen pond. At one moment, when Max is skating away from the shore at 8.2 m/s and Maya is skating towards the shore at 4.6 m/s, they collide and bounce off each other without falling. If Maya rebounds at 3.4 m/s, what is Max's velocity after their collision?(15kg*-8.2m/s+12kg* 4.6m/s=15kg*V+12kg*-3.4m/s)
1.8 m/s away from the shore
A 5 kg shark swimming at 1 m/s swallows an absent-minded 1kg fish swimming toward it at 4 m/s. The speed of the shark is (hint:(5*1)+(1*-4)=6v)
1/6 m/s
Consider massive gliders that slide friction-free along a horizontal air track. Glider A has a mass of 1 kg, a speed of 1 m/s, and collides with Glider B that has a mass of 5 kg and is at rest. If they stick upon collision, their speed after collision will be(hint:(1*1)+(5*0)=6v)
1/6 m/s
A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with
10 times as much force
An airplane travels at 141 km/h toward the northeast. What is its component of velocity due north?
100 km/h
A projectile is launched vertically at 100 m/s. If air resistance can be ignored, at what speed will it return to its initial level?
100 m/s
One end of a rope is pulled with 100 N. Well the opposite and also is Paul's with 100 and. The tension in the rope is
100N
When a baseball player bats a ball with a force of 1000 N, the reaction force that the ball exerts against the bat is
100N
About 40 J is required to push a crate 4 m across a floor. If the push is in the same direction as the motion of the crate, the force on the crate is about
10N
The force of friction on a sliding object is 10N. The force needed to maintain a constant velocity is
10N
What is the net force that acts on a 10N free falling object?
10N
Phil leans over the edge of a cliff and throws a rock upward at 5m/s. Two seconds later, neglecting air resistance, the rock's speed would be
15 m/s
If a stone falls to the bottom of a mineshaft in six seconds, then the depth of the shaft is about
180m
An apple at rest weighs 1 N. The net force on the apple when it is in free fall is
1N
What is the approximate weight of a quarter-pound hamburger after it is cooked?
1N
A projectile is launched upward at an angle of 70° from the horizontal and strikes the ground a certain distance downrange. For what other angle of launch at the same speed would this projectile land just as far away?
20
Max (15 kg) and Maya (12 kg) are ice-skating on a frozen pond. While standing at the center of the pond, Maya throws a 1.5-kg snowball at Max and, as a result, recoils away from Max at 2.5 m/s. With what speed did Maya throw the snowball at Max?(0=12kg* -2.5m/s+1.5kg*V)
20 m/s
What horizontally-applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight(hint: weight is 4000 N, so friction would be 2000N)
2400N(F=ma, f-2000=400)
A 50kg firefighter is on a ladder 10 meters above the ground. When the firefighter descends to 5 meters above the ground, the firefighter's gravitational potential will decrease by(PE:5000-500(5))
2500J
A roller coaster ride with 6 passengers takes 3 min. NEGLECTING FRICTION, a similar ride with 12 passengers aboard would take
3 min (all things fall at the same rate)
When a karate chop breaks a board with a 3000-N blow, the amount of force that acts on the hand is
3000N
If you are driving at 20 m/s and slam on your brakes and skid at 0.5g to a full stop, the skidding time in seconds is
4(velocity=acceleration x time)
The work done in pushing a TV set a distance of 2m with an average force of 20N is
40J
An asteroid exerts a 360-N gravitational force on a nearby spacecraft. If the spacecraft moves to a position three times as far from the center of the asteroid, the force will be(1/9 of 360 because of the inverse square law)
40N
What is the distance fallen for a freely falling object from a rest position 3s after?
45m
If you throw a stone horizontally from the top of a cliff, one second after leaving your hand its vertical distance below the top of the cliff is
5 m
1/2 second after starting from rest, a free falling object will have a speed of about
5 m/s
About how far below a straight-line path does a satellite in close Earth orbit fall in the first second of fall?
5 m/s
Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, one second later the rock's speed is
5 m/s
neglecting air resistance, a ball projected straight upward so it remains in the air for 10 seconds needs an initial speed of
50 m/s
A jack system will increase the potential energy of a heavy load by 1000 J with a work input of 2000 J. The efficiency of the jack system is
50%
How much power would be involved if you lifted a 50N rock a distance of 10m in 1s(P:W/t)
500 W
How much work is done on a 50N rock that you lift 10m straight up(hint:W=Fd)
500J
What is the kinetic energy of an object with a mass of 10 kg traveling at a speed of 10 m/s?
500J
What is the distance fallen for a freely falling object from a rest position 1s after?
5m
Phil leans over the edge of a cliff and throws a rock upward at 5m/s. One second later, neglecting air resistance, the rock's speed would be
5m/s(downward)
A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is
9.8 m/s^2
What is the gain in speed per second for a freely falling object?
9.8 m/s^2
A 1-kg mass at the Earth's surface weighs
9.8N
How much time does it take for a complete revolution of a satellite in close orbit about Earth?
90 minutes
What happens to acceleration when an object is in free fall?(hint:weight=mg)
A=mg-R/m
Who gathered the data that showed planets traveling in elliptical paths around the Sun? Who discovered elliptical orbits? Who explained them?
Brahe, Kepler, Newton
Earth's gravitational field is strongest at _______
Earth's surface
Why does the force of gravity change the speed of a satellite in an elliptical orbit?
Gravity slows the satellite as it moves away and speeds it up on its return
At what part of an elliptical orbit does an Earth satellite have the greatest speed? The lowest speed?
Greatest nearest Earth; lowest furthest from Earth
Consider the video demonstration that you just watched. A more complete explanation of what you saw will be possible after covering Newton's laws. For now, consider the following question: How would the result of this experiment change if we replaced the ball with another one that had half the mass? Ignore air resistance.
The ball would still land in the cart
What would the magnitude of the gravitational field be anywhere inside a hollow, spherical planet?
Zero N/kg
A golf ball is thrown at and bounces backward from a massive bowling ball that is initially at rest. After the collision, compared to the golf ball, the bowling ball has more a)momentum and more kinetic energy b)momentum, but less kinetic energy c)kinetic energy, but less momentum
a
A shoe on an inclines surface barely remains at rest the friction equals the a)component of mg parallel to the surface b)weight mg of the shoe c)component of mg perpendicular to the surface
a
Nellie hangs motionless by one hand from a clothesline. Which side of the line, a or b, has the greater tension?
a
Newton's Cradle consists of an aligned row of identical elastic balls suspended by strings so they barely touch one another. When two balls are raised from one end and released, they strike the row and two balls pop out from the other end. If instead, one ball popped out with twice the speed of the two, this would violate a)energy conservation b)momentum conservation c)both
a
Which has greater kinetic energy? a)a car of half the mass traveling at 60 km/hr or b)a car traveling at 30 km/r
a
A roller coaster is initially pulled up by a hill from Point A, where it has no potential energy, to Point B. It then rolls down a hill, around the loop at points C and D, and comes to rest at Point E(Points A, C, and E are all the same level). The track from Point A to Point B is not as steep as from Point B to Point C. The roller coaster is designed this way so that
a smaller force is needed to get the car up the hill
How can a projectile "fall around the Earth"? a)A projectile can "fall around Earth" if the distance it falls matches the curvature of Earth. b)The projectile falls 5 m for every 8 km and so does Earth. c)In a circular orbit around a spherical planet, the force and the fall are always toward the center.
all of the above
The ram of a pile driver drops onto the top of an iron beam, driving it partway into the ground. The distance that the beam sinks into the ground depends on the a)initial potential energy of the ram b)initial height of the ram c)kinetic energy of the ram when it first
all of the above
Both Newton and Kepler considered forces on the planets. Kepler hypothesized the direction of the forces was
along their directions of travel
Rate this statement: No force due to Earth's gravity acts on astronauts inside the orbiting space station.
always false
Art museums use weaker wires than those used in homes because paintings in museums
are suspended by pairs of vertical wires
suppose a free fall ride were in a vacuum, the student's speed at the finish of the fall would be a)zero b)greater than her speed in the air c) less than her speed in the air d) the same as than her speed in the air
b
Which two factors mainly affect ocean tides on Earth? a)the pull of distant planets b)the Moon c)Earth's revolution about both the Moon and the Sun d)the Sun
b, d
Nellie Newton pulls her sled by a rope that is 45° to the horizontal. The horizontal and vertical components of force are a)equal in magnitude b)each about .7 times the force she exerts on the rope
both
Which task requires more work? a) lifting the 50-kg sack 2 meters b) lifting the 25-kg sack 4 meters
both the same
The greater efficiency achieves with the curved blades of a Pelton wheel is due to
bouncing
Power is defined as the a)work done times the time it takes to do that work b)force on an object times the distance an object moves c)work done on an object divided by the time taken to do that work d)force on an object divided by the time the force acts
c
The total momentum of a flock of identical birds could be zero only if the birds are a)very tired and coming down to rest b)all flying in the same direction c)all flying in different directions d)taking off from the ground
c
Which of these is not a form of solar energy? a)hydroelectric power b)wind energy c)geothermal energy d)fossil fuel energy
c
When Burl and Paul stand on opposite ends of a sign-painting scaffold, the tensions in the supporting ropes
depend on the relative weights of Burl and Paul.
The force that propels a cannonball when fired from a cannon is
equal and opposite to the force the ball exerts on the cannon
The speed of a satellite orbiting Earth is given by v=sqrt(GM/d). Escape speed from Earth is given by v=sqrt(2GM/d), where in both cases G is the gravitational constant, M is Earth's mass, and d is the distance from Earth's center. If a satellite's kinetic energy could double it could
escape Earth
A vertically oriented rocker that is able to sustain a continuous upward velocity of 8 km/s will
escape from Earth
A moving van with the stone lightly glued to the midpoint of its ceiling moves at a constant velocity. When the glue gives way, the stone falls and hits the floor
exactly below the midpoint of the ceiling
When a rocket forces exhaust gases downward, the exhaust gases
exert an upward force on the rocket
When a boxer hits a punching bag, the strength of his punch depends on how much force the bag can
exert on the boxer's fist
The acceleration of an object is inversely proportional to the net force acting on the object
false
The energy an object has by virtue of its location is called the object's kinetic energy.
false
The speed of an object dropped in air will continue to increase without limit until it hits the ground
false
Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment?(The ball will spend twice as much time in the air (t=2v0y/g, where v0y is the ball's initial upward velocity). When subtracting the horizontal distance the cart travels in time,t, from the horizontal distance the ball travels in time,t, the term involving initial velocity of the cart (which is also the horizontal velocity of the ball) cancels out, leaving only d=12 axt2 (where ax is the cart's horizontal acceleration).)
four times as far
A roller coaster is initially pulled up by a hill from Point A, where it has no potential energy, to Point B. It then rolls down a hill, around the loop at points C and D, and comes to rest at Point E(Points A, C, and E are all the same level). Suppose that for an added thrill you wanted to have the car moving at twice its present speed at the bottom of the first hill. To accomplish this, you would have to make the hill
four times as high
What is the ratio force/mass for free falling bodies?
g
as a ball bounces from a floor, it's acceleration off the floor between bounces is
g
For a planet of uniform density, how would the magnitude of the gravitational field halfway to the center compare with the field at the surface?
g/2 m/s2
As water drops for a steady rate from a leaking faucet they
get farther apart
A roller coaster is initially pulled up by a hill from Point A, where it has no potential energy, to Point B. It then rolls down a hill, around the loop at points C and D, and comes to rest at Point E(Points A, C, and E are all the same level). The greater part of the work done on the roller coaster as the car is pulled from Point A to Point B goes into
gravitational potential energy
compared with hang time on earth, hang time on the moon would be
greater
if a free falling object were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before
velocity acquired
gt(acceleration x time)
The center of a long uniform log is raised to shoulder level while the other end is on the ground. If instead the end of the log is raised to shoulder level, the work required is
half
when Nelly Newton hangs by the end of a rope draped over a large pulley, the tension in each supporting string is
half her weight
A pair of air pucks on an air table are set in motion when a compressed spring between them is released. If one puck moves with twice the speed of the other, the mass is
half the mass of the other
A car by itself is capable of a certain maximum acceleration. When it tows a car of the same mass, its maximum acceleration is(hint:double the mass)
halved
An object following a straight-line path at constant speed
has zero acceleration
When Monkey Mo is suspended at rest by holding a rope with one hand and the side of his cage with the other, all the force vectors that act on him
have a vector sum of zero
violent motion (Aristotle)
imposed motion; the result of forces that pushed or pulled
Law of conservation of momentum
law stating that the total momentum of a system does not change in the absence of an external force
Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter
lengthened time of contact
A ball is thrown upwards and caught when it returns. Compared with its initial speed and in the presence of air resistance, the speed with which it is caught is
less
A pair of equal-length vectors at right angles to each other have a resultant. If the angle between the vectors is greater than 90 degrees, their resultant is
less
When you weigh yourself on a bathroom scale on a slight incline instead of a level surface, your weight reading on the scale would be
less
An object has gravitational potential energy due to its
location
Three kids pull on a toy. Kim pulls with a force of 30 N north, Jim pulls with a force of 30 N south, and Tim pulls with a force of 15 N east. The acceleration of the toy is
need more info(no time)
All places on Earth would have high tides at the same instant if the a)moon did not rotate b)sun did not revolve a)moon did not revolve d)sun did not rotate
none of the above
Wiley car travels around a circular track at a constant speed, it's a) inertia is zero b)acceleration is zero c)velocity is zero
none of the above
an instrument to measure the distance traveled
odometer
The foci of the elliptical path for an Earth satellite are __________
one at Earth's center and the other elsewhere
elastic collision
one in which there is no net loss of total kinetic energy
The tangential velocity of an Earth satellite is its velocity
parallel to the surface of Earth
For lunar tides to occur in the human body
parts of the body would have to be appreciably closer to the Moon than other parts.
perigee
point in an orbit that is closest to the earth
Galileo's interpretation of motion differed from Aristotle's in that Galileo emphasized
rates of time
Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a bullseye marked on the floor a horizontal distance away. Compared to the time for the ball to simply drop vertically from the bench, the time in the air for Dr. Chuck's projected ball is
the same
The brakes of a speeding truck are slammed on and it skids to a stop. If the truck were heavily loaded so that it had twice the total mass, the skidding distance would be
the same
If the free fall ride were in a vacuum and the student dropped a small bat at point A, the speed of the bat would be
the same as her speed at Point B
To catch a fast-moving ball, you must extend your hand forward before contact with the ball and let it ride backward in the direction of the ball's motion. Doing this reduces the force of contact on your hand principally because the
time of contact is increased
Air resistance is caused by friction between the air and an object moving through the air
true
The energy an object has by virtue of its motion is called the object's kinetic energy.
true
The ratio of output force to input force of a simple machine is called the efficiency of the machine.
true