conceptual physics fall final
A hydraulic jack is used to lift objects such as automobiles. If the input force is 200 N over a distance of 1 meter, the output force over a distance of 0.1 meter is ideally
2000 N
The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 seconds is
2000 N
A block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the force of friction between the block and the surface?
6 N
The power required to exert 4-N force over 3 meters in 2 seconds is
6 W
The change in momentum that occurs when 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s is
6 kg m/s
A 5000-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?
6 m/s
A car's speed 3 seconds after accelerating from rest at 2 m/s^2 is
6 m/s
A car starts from the rest and after 7 seconds it is moving at 42 m/s. What is the car's average acceleration?
6 m/s^2
If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is
6 m/s^2
How much power is expended if you lift a 60 N crate 10 meters in 1 second?
600 W
A bullet is fired horizontally with an initial velocity of 300 m/s from a 20-m high tower. If air resistance is negligible, the bullet hits downrange about
600 m
According to Kepler, the paths of planets about the Sun are
ellipses
The conversion of energy applies to satellites in
elliptical and circular orbit
The force of gravity does work on a satellite when it is in
elliptical orbit
A moving object has
energy; speed; velocity; momentum
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 force with which Earth pulls on the moon is
equal in magnitude to the force that Moon pulls on the Earth
A firecracker bursts while freely falling. The combined momentum of its fragments
equals the momentum of the firecracker at the time of burst
A moving van with a stone lightly glued to the midpoint of its ceiling smoothly moves at constant velocity. When the glue gives way, the stone falls and hits the floor
exactly below the midpoint of the ceiling
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
Science later greatly advanced when Galileo favored
experiment over philosophical discussions
A karate chop is more effective if one's hand
extends the time upon impact
During an eclipse of the Sun (when the moon and the Sun are totally lined up) the high ocean tides on Earth are
extra high
When you drop a rubber ball on the floor it bounces back. The force exerted on the ball to produce bouncing is by the
floor
If you whirl a tin can on the end of a string and the string suddenly breaks, the can will
fly off, tangent to its circular path
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
Newton had the insight to see that the
force on the moon has the same nature as the force on an apple
Torque is defined as
force times lever arm
A bicycle that travels twice as fast as another when braking to a stop will skid
four times as far
Two identical arrows, one with the speed of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates
four times as far
The force of Earth's gravity on a capsule in space increases as it comes closer. When the capsule moves to half its distance, the force toward Earth is then
four times greater
Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has
four times the kinetic energy
An Earth satellite is simply a projectile
freely falling around Earth
A vehicle undergoes acceleration when it
gains speed, loses speed, or changes its direction
As water drops fall at a steady rate from a leaking faucet they
get farther apart
As Bronco Brown steps off a hovering high-flying helicopter and falls through the air, he experiences
an increasing speed, an impulse, and a decreasing acceleration
When a skateboarder pushes on a wall,
an interaction occurs between the skateboarder and the wall; the wall pushes on the skateboarder; such a push couldn't happen unless the wall pushed on the skateboarder
At equilibrium on a bathroom weighting scale, the downward pull of gravity on you is balanced by
an upward support force
When air drag affects the motion of projectiles, they don't travel
as high or as far
If you toss a coin straight upward while in a train moving at a constant velocity, the coin will land
as if you were at rest
A bullet fired horizontally from a rifle begins to fall
as soon as it leaves the barrel
Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The combined wreck moves in a direction
at 45 degrees to the direction of either car before collision
Neglecting friction, a small and a large block of ice begin sliding down an incline together. The larger block reaches the bottom
at the same time as the small block
A vertically-held sledge hammer is easier to balance when the heavier end is
at the top, away from your hand
Earth satellites are typically more than 100 km high so as to be above Earth's
atmosphere
If no external forces act on a moving object, it will
continue moving at a steady pace
If no external forces act on a moving object, it will
continue moving at the same speed
When you do somersaults, you'll more easily rotate when your body is
curled into a ball shape
If Earth's mass decreased to one-half its original mass with no change in radius, then your weight would
decrease to half
Suzie Skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration
decreases
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
On each given day and location, tides rise and fall at
different times
The net force exerted on a car traveling in a circular path at constant speed is
directed toward the center of the curve
The two measurements necessary for calculating average speed are
distance and time
Compared with a force, a torque involves
distance from an axis of rotation, rotation, and leverage
If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will
double
A heavy track and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared with the force that stops the car, the force needed to stop the truck is
greater
If an object falling freely 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
According to Newton, the greater the masses of interacting objects, the
greater the gravitational force between them
Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is
greater with the brick wall
Consider a string with several rocks tied along its length at equally spaced intervals. You whirl the string overhead so that the rocks follow circular paths. Compared with a rock at the end of the string, a rock at the middle moves
half as fast
A clerk can lift cylindrical packages 1 meter vertically, or roll them up a 2-meter-long ramp to the same elevation. With the ramp, the applied force required is about
half as much
A skydiver's terminal velocity will be greatest if she falls
head first
Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
heavier object
The lift experienced by a helicopter involves an action-reaction pair of forces between the
helicopter blades and the air
Nellie's weight and normal force usually have the same magnitude when she stands on a
horizontal surface
A softer landing occurs when a falling object bounces from a surface
in an extended time
According to Kepler, the line from the Sun to any planet sweeps out equal areas of space
in equal time intervals
A hockey puck sliding at constant velocity across the ice is
in equilibrium
If you toss a coin straight upward in train that shows while the coin is in the air, the coin is in the air, the coin will land
in front of you
Which has zero acceleration? An object
in mechanical equilibrium; moving at a constant velocity; at rest
A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move. The bowling ball is set in motion with a momentum of
more than 1 unit
Twelve seconds after starting from rest, a freely-falling cantaloupe has a speed of
more than 100 m/s
If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be
more than the golf ball
A solitary boy cannot balance on a seesaw with its fulcrum at its midpoint. If the fulcrum is moved to one-quarter the distance from the boy, balance is achieved when the weight of the boy is
more than the weight of the seesaw
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
An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will
move in the opposite direction at a lower speed
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
Minimal orbital speed about Earth is about 8 m/s, and about the Moon is
less than 8 m/s
An object has gravitational potential energy due to its
location
An object is thrown vertically into the air. In this case air resistance affects motion. Compared with its time for ascent, the time for its descent is
longer
If you can't avoid being hit by a fast-moving object, you'll suffer a smaller contact force if you can extend that force over a
longer time
From Earth, one satellite appears to overtake another. The faster satellite is
lower
A force is a vector quantity because it has both
magnitude and direction
A kilogram is a measure of an object's
mass
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
mass; volume; inertia
A rock is thrown vertically into the air. At the top of its path the net force on it is
mg
A primary difference between momentum and kinetic energy is
momenta can cancel; kinetic energy cannot
You experience weightlessness
momentarily when you step off a chair, in a freely falling elevator, and in the absence of a supporting surface
A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater
momentum
If all-electric car has kinetic energy, then it also must have
momentum
If the speed of a motor scooter doubles, what also doubles?
momentum
If you were to weigh yourself in an elevator that is accelerating upward, compared to your ordinary weight you would weigh
more
A fan attached to an ice sail craft stalled on a windless day blows air into the sail that bounces backward upon impact. The boat
moves in the direction of the wind impact force
An object that has kinetic energy must be
moving
To produce an acceleration to a system there
must be a net force on the system
Horses with the greatest linear speed on a merry-go-round are located
near the outside
An industrial flywheel has a greater rotational inertia when most of its mass is
nearer the rim
An Earth satellite in an elliptical orbit travels faster when it is
nearest Earth
According to Kepler, the speed of a planet is slowest when it is
neither farthest or closest from the sun, for speed is a constant
The best time for digging clams (when the low tide is extra low) is during the time of the
new or full moon
An object's weight is properly expressed in units of
newtons
A gymnast performing somersaults in a high-flying plane moving at constant velocity needs to make
no adjustments
If the Moon were four times as massive but twice as far from Earth, high tides on Earth would be
no different
Weigh yourself on a weighing scale and the scale shows your normal weight. If you carefully stand on your tiptoes, the scale reading will be
no different
When a rocket ship gaining speed in outer space runs out of fuel, it
no longer gains speed
An astronaut at Earth's surface has a mass of 50 kg and a weight of 500 N. If she were floating freely inside a space habitat in remote space, she would have
no weight and the same mass
If the Sun became twice as massive, your attraction to the Sun would double and your weight as measured on Earth would
not change
An object will fall over if its center of gravity is
not over its area of support
A pair of wires support a heavy painting. Tension in the wires is greater when they are
not vertical
What prevents satellites such as the ISS from falling?
nothing
The equilibrium rile, equilibrium = 0, applies to
objects or systems in uniform motion in a straight line and objects or systems at rest
Which objects roll down an incline with the greatest acceleration?
objects with small rotational inertia
A pair of action-reaction force always
occur simultaneously
A hockey puck sliding across the ice finally comes to rest because
of friction
The force of gravity on you is greatest when you are standing
on Earth's surface
A ball rolling down an incline has its maximum kinetic energy at
the bottom
A boy plays solitary seesaw by placing the seesaw's fulcrum one-eighth the distance from where he sits at one end. Which weighs more: the boy or the seesaw?
the boy
A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which one will hit the ground first?
the dropped one
Two identical freight cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple together, and roll away in the direction of
the faster car
Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter?
the filled jar
Your weight as measured on your bathroom scale is
the force due to gravity on you
If you try to touch your toes while standing flat against a wall, you probably will fall over. The reason this happens is that
your center gravity is not located directly above your support area
While you are standing in the aisle of a bus, the driver suddenly makes a left turn. You lurch to the right due to
your tendency to keep moving forward
Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour. Which of the following is NOT true?
your velocity is constant
If you were to weigh yourself in an elevator that is in free fall, compared to your ordinary weight, you would weigh
zero
Recoil is noticeable if we throw a heavy ball while standing on roller skates. If instead we go through the motions of throwing the ball but hold onto it, our new recoil will be
zero
The net force on any object in equilibrium is
zero
Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
zero
When a falling object has reached its terminal velocity, its acceleration is
zero
A boulder following a straight-line path at constant velocity has
zero acceleration
John weighs 150 N and sits on his big brother's shoulders. Big brother weighs 400 N. The support force supplied by the floor must be
zero and rope tension is 50 N
When a baseball player bats a ball with a force of 1000 N, the reaction force that the ball exerts against the bat is
1000 N
The mass of a lamb that weighs 110 N is about
11 kg
A 10-N falling object encounters 4 N of air resistance. The net force on the object is
6 N
An object falls freely from rest on a planet where the acceleration due to gravity is 30 m/s^2. After 5 seconds, the object will have a speed of
100 m/s
An 80-km/h airplane caught in a 60-km/h crosswind has a resultant speed of
100-km/h
A 10-N falling object encounters 10 N of air resistance. The net force of the object is
0 N
A ball is thrown straight up. At the top of its path its instantaneous speed is
0 m/s
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of
0 m/s
A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration becomes
0 m/s^2
You stand on your skateboard and exert a 50-N push on the wall next to you. If your mass is 60 kg you'll momentarily accelerate from the wall at about
0.8 m/s^2
A 1-kg rock is suspended from the tip of a horizontal meter stick at the 0-cm mark so that the meter stick barely balances like a seesaw when its fulcrum is at the 25-cm mark. From this information, the mass of the meter stick is
1 kg
A 10-kg block is pushed across a horizontal surface with a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is
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
The time it takes a projectile fired straight up at 10 m/s to reach the top of its path is about
1 second
A piece of putting moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. Both move with a combined momentum of
1 unit
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
1/2 m/s
A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at
1/3 m/s
A 5-kg shark swimming at 1 m/s swallows an absent-minded 1-kg fish swimming toward it at 4 m/s. The speed of the shark after his meal is
1/6 m/s
A block pulled to the left with 15 N and to the right with 5 N at the same time experiences a net force of
10 N
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
10 N
The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is
10 N
The support force of a 10-N book at rest on a table is
10 N
A bird flying at 8 km/h in a 6 km/h crosswind has a resultant speed of
10 km/h
If a freely-falling object were equipped with a speedometer, its speed reading would increase each second by about
10 m/s
If an object falling freely were equipped with a speedometer, its speed reading would increase each second by about
10 m/s
A rock is thrown vertically into the air. At the top of its path, its acceleration is
10 m/s^2
When a ball thrown straight upwards reaches the very top of its path, its acceleration is
10 m/s^2
A push on a brick accelerates it. Neglecting friction, equally accelerating a 10-kg brick requires
10 times as much force
A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is
10%
A weight watcher who normally weighs 400 N stands up on top of a very tall ladder so she is one Earth radius above Earth's surface. How much is her weight there?
100 N
One end of a rope is pulled with 100 N, while the opposite end also is pulled with 100 N. The tension in the rope is
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 second later?
100 m
Phil applies 100 N to a pulley system and raises a load one-tenth of his downward pull. Ideally, the weight of the load is
1000 N
Suppose a moving car has 3000 J of kinetic energy. If the car's speed doubles, how much kinetic energy will it then have?
12,000 J
Suppose the gravitational force between two massive spheres is 30 N. If the distance between the spheres is cut in half, what is the force between the masses?
120 N
A pair of 10-N vectors at right angles to each other has a resultant of about
14 N
Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is
14 m/s
An airplane that flies at 100 km/h in a 100 km/h crosswind has a ground speed of
141 km/h
A tree slump is pulled northward by a 10-N force at the same time a 25-N force pulls it southward. The resultant force has a magnitude of
15 N
A tow truck exerts a force of 3000 N on a car, which then accelerates at 2 m/s^2. What is the mass of the car?
1500 kg
The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is
16 kg
If a stone falls to the bottom of a mineshaft in 6 seconds, then the depth of the shaft is about
180 m
The minimum number of forces that act on a book resting on a table is
2
The power expended doing 100 J of work in 50 seconds is
2 W
A 2-kg box of taffy candy has 40 J of potential energy relative to the ground. Its height above the ground is
2 m
The circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second then its linear speed is
2 m/s
If the Moon were covered with water, tidal effects caused by Earth would find the Moon with
2 tidal bulges
A 5000-kg freight car moving at 2 m/s collides with a 10,000-kg freight car at rest. They couple upon collision and move away at
2/3 m/s
When you walk at an average speed of 4 m/s, in 5 seconds you'll cover a distance of
20 m
A ball player wishes to determine pitching speed by throwing a ball horizontally from an elevation 5 m above ground level. The ball lands 20 m downrange. The player's pitching speed is about
20 m/s
A car has a mass of 1000 kg and accelerates at 2 m/s^2. What net force is exerted on the car?
2000 N
The airspeed of an airplane is 200 km/h. When it is caught in a 200 km/h crosswind, its speed across the ground below is
283 km/h
A 60-N object moves at 1 m/s. Its kinetic energy is
3 J
The speed of a 4-kg ball with a momentum of 12 kg m/s is
3 m/s
Nellie pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration?
3.0 m/s^2
Two projectiles 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 one fired at
30 degrees
Neglecting air resistance, how fast must you toss a ball straight up in order for it to take 6 seconds to return to its initial level?
30 m/s
A 500-N parachutist opens his chute and experiences an air resistance force of 800 N. The net force on the parachutist is then
300 N upward
When a karate chop breaks a board with a 3000-N blow, the amount of force that acts on the hand is
3000 N
A motorcycle of mass 100 kg slowly rolls off the edge of a cliff and falls for three seconds before reaching the bottom of a gully. Its momentum upon hitting the ground is
3000 kg m/s
10 seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration?
4 m/s^2
How much work is done on a 20-N crate that you lift 2 m?
40 J
The work done in pushing a TV set a distance of 2 m with an average force of 20 N is
40 J
A projectile is fired into the air at an angle of 50 degrees above ground level and hits a target downrange. It will also hit the target if fired at an angle of
40 degrees
At one instant a heavy object in air is moving upward at 50 m/s. One second later its speed is approximately
40 m/s
Burl and Paul have a total weight of 1300 N. The tensions in the supporting ropes that support their weight scaffold add to 1700 N. The weight of the scaffold it's self must be
400 N
A hummingbird flying at 4 km/h that gets caught in a 3-km/h crosswind has a resultant speed of about
5 km/h
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
A vertical vector of 3 units combined with a horizontal vector of 4 units has a resultant of
5 units
A 5-kg fish swimming at 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is
5/6 m/s
The resultant of a 40-N force at right angles to a 30-N force is
50 N
A toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed using 1000 J of work, is
50 W
Joshua is attracted toward Earth by a 500-N gravitational force. The Earth is attracted toward Joshua with a force of
500 N
Phil stands at rest with both feet on a scale that reads 500 N. When he gently lifts one foot, the scale reads
500 N
Suzie Skydiver, who weighs 500 N, reaches a terminal velocity of 90 km/h. The air resistance on Suzie is then
500 N
What is the force of gravity on a 500-N woman standing on Earth's surface?
500 N
Danny Diver weighs 500 N and steps off a diving board 10 m above the water. Danny hits the water with kinetic energy of
5000 J
Two 5000-kg rail cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, and roll together with a combined momentum of
5000 kg m/s
An arrow in a bow has 70 J potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot?
70 J
A meter stick is balanced at the 50-cm mark. You tie a 30-N weight at the 20-cm mark. Where should a 40-N weight be placed so the meter stick will again be balanced?
72.5-cm mark
How many joules of work are done on a box when a force of 25 N pushes it 3 m?
75 J
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 degrees
A frictionless inclined plane is 8.0 m long and rests on a wall that is 2.0 m high. How much force is needed to push a block of ice weighing 300.0 N up the plane?
75.0 N
How much power is required to do 40 J of work on an object in 5 seconds?
8 W
A 2-kg ball is held 4 m above ground. Relative to the ground its potential energy is
80 J
A ball staring from rest at the top of an inclined plane accelerates at 2 m/s^2 and reaches the bottom of the plane at 3 seconds. What is the length of the plane?
9 m
An 80-km/h airplane flying in the same direction as a 10km/h tail wind has a groundspeed of
90 km/h
A motorcycle moving at 50 km/h skids 10 m with locked brakes. How far will it skid with locked brakes when traveling at 150 km/h?
90 m
The first scientist to be credited for postulating that Earth circled the Sun was
Copernicus
Which is greater, the gravitational force between Earth and the moon, or the force between Earth and the sun?
Earth-sun
The first scientist to introduce the concept of inertia was
Galileo
Which is most responsible for Earth's ocean tides?
Moon
The Moon does not crash into Earth because
Moon has a sufficient tangential speed
The impulse-momentum relationship is a direct result of
Newton's 2nd Law
Which pulls on the oceans of Earth with a greater force?
Sun
Project a cannonball from atop Newton's hypothetical mountain at 8 m/s and it orbits Earth. Project it at 9 m/s and the shape of its orbit is
an ellipse
It is correct to say that impulse is equal to
a corresponding change in momentum
A machine that promises more energy output than input is
a fantasy
Suppose an object is in free fall. Each second the object falls
a larger distance than in the second before
theory
a synthesis of a large body of well-tested knowledge
A package falls off 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
The rotational inertia of a pencil is greatest about an axis
about its ends, like a pendulum
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
above a place of support
If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object
accelerates in the direction of the applied force
In the absence of air resistance, objects fall at constant
acceleration
If Nellie hangs from a horizontal bar that is supported by four vertical ropes, the tension in the ropes
add to equal her weight
When you stand at rest on a pair of bathroom scales, the reading on each scale
add up to equal your weight
The earliest and most influential Greek philosopher was Aristotle, who among many contributions taught that
all motion is either natural or violent; the four elements are earth, water, air, and fire; violent motion requires a sustained push or pull
We do not observe tides in a community swimming pool because
all parts of it are practically the same distance from the moon
Action and reaction pairs of forces
always act simultaneously
Newton discovered
that gravity is universal
When you quickly jerk a cart forward that has a ball resting in the middle, the
back of the cart hits the ball
If Burl carries Paul piggy-back while standing in the middle of a scaffold, the tensions in the two supporting ropes would
be equal
If you toss a coin straight upward in train that gains speed while the coin is in the air, the coin will land
behind you
You can swing your legs to and from more frequently when your legs are
bent
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 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
Which produces more force: driving into a very massive concrete wall with no "give," or having a head-on collision with an identical car moving toward you at the same speed?
both the same
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
A karate chop is more efficient if one's hand
bounces upon impact
The greater efficiency achieved with the curved blades of a Pelton wheel is due to
bouncing
Stand a broom upright on the end of its pole and let it topple to the floor. Repeat, but with the bristles end on the floor. The faster fall will be the broom standing on its
bristles-end
To make a profit a buyer purchases metal by weight at one altitude and sells it at the same price per pound at another altitude. The supplier should
buy at a high altitude and sell at a low altitude
A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the
cannon has much more mass than the cannonball
When you rub your hands together, you
cannot push harder on one hand than the other
Toss a baseball bat into the air and it wobbles about its
center of mass
The kinetic energy of a planet is maximum when it is
closest to the Sun
A coin and a ring roll down an incline at the same time. The one to first reach the bottom is the
coin
A common pulley acts similar to a
common lever
Earth's primary energy source is
the Sun
If the mass of Earth somehow increased with no change in radius, your weight would
increase also
When a boxer moves into an oncoming punch, the force experienced is
increased
As the rotational speed of a space habitat increases, the weight of people inside
increases
As two objects moving toward each other due to gravity get closer, the acceleration of each
increases
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
The distance a freely falling bowling ball falls each second
increases
Two objects more toward each other due to gravity. As the objects get closer and closer, the force between them
increases
When a twirling ice skater brings her arms inward, her rotational speed
increases
While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity
increases
When the distance between two stars decreases by one-third, the force between them
increases to nine times as much
If your automobile runs out of fuel while driving, the engine stops. You don't come to an abrupt stop due to
inertia
The resistance an object has to changes in its rotational state of motion is called rotational
inertia
The speedometer of an automobile reads
instantaneous speed
When you look at the speedometer in a moving car, you can see the car's
instantaneous speed
A car travels in a circle with constant speed. The net force on the car
is directed toward the center of the curve
For every action force, there must be a reaction force that
is equal in magnitude
A satellite coasting at constant speed in a circular orbit
is nevertheless accelerating
If the net force on a car is tripled, the cart's acceleration
is three times as much
Whenever the net force of an object is zero, its acceleration
is zero
As soon as a ball rolls off the edge of a table
it is not acted on by any horizontal forces
When the potential energy of a satellite decreases
its kinetic energy correspondingly increases
Galileo taught us that if you roll a ball along a level surface it will
keep rolling if friction is absent
What values vary for satellites in elliptical orbit?
kinetic energy, speed, and acceleration
If the Moon had twice as much mass and still orbits Earth at the same distance, ocean bulges on Earth would be
larger
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 upward 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
Ideally, a ball is thrown up at an angle and lands downrange. Because of air resistance, the distance reached 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 will be
less
A car traveling along the highway brakes to a stop over a certain distance. More braking force is required if the car has
less stopping distance, more momentum, and more mass
A ball is thrown into the air with 100 J of kinetic energy, which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is
less than 100 J
A lunar month is about 28 days. If the moon were closer to Earth than it is now, the lunar month would be
less than 28 days
The main reason ocean tides exist is that Moon's pull is stronger
on water closer to it than on water farther away
A car by itself is capable of a certain maximum acceleration. When it tows a car of the same mass its maximum acceleration is
one half
The force of Earth's gravity on a capsule in space will lessen as it moves farther away. If the capsule moves twice its distance, the force toward Earth becomes
one-fourth
Half-way to the center of a planet of uniform density, your weight compared to that at the surface would be
one-half
According to Newton, when the distance between two interacting objects doubles, the gravitational force is
one-quarter
A parallelogram is a four-sided figure with opposite sides that are
parallel
Acceleration is greater for a satellite when it is the
pedigree (closest point)
A rocket coasts in an elliptical orbit around Earth. To attain escape velocity using the least amount of fuel in a brief firing time, should it fire off at the apogee, or at the pedigree?
pedigree, where it is closest and fastest
The fastest moving planet in a solar system is the
planet nearest to the Sun
The force of gravity acts on all apples on an apple tree. Some apples are twice as far from the ground as others. For the same mass these twice-as-high apples have
practically the same weight
When you walk, you push on the floor to the left and the floor
pushes you to the right
When a star collapses to form a black hole, it's mass
remains the same
A ring and a disk both at rest roll down a hill together. Which rolls slower?
ring
Two people are balanced on a seesaw. If one person leans inward towards the center of the seesaw, that person's end of the seesaw tends to
rise
A projectile that is fixed vertically from the surface of Earth at 5 m/s will
rise and fall back to Earth's surface
The force exerted on the tires of a car that directly accelerate it along a road is exerted by the
road
When railroad tracks make a curve, the outer track is longer. This means a wheel that rides on the outer track needs to somehow
roll faster than the wheel on the inner track
"Centrifugal forces" are an apparent reality to observers in a reference frame that is
rotating
Centrifugal forces are an apparent reality to observers in a reference frame that is
rotating
A torque acting on an object tends to produce
rotation
Monkey Mo hangs from the middle of a horizontal rope. Tension in the rope is greatest if the rope
sags very little
A pair of toy freight cars, one twice the mass of the other, fly apart when a compressed spring that joins them is released. The spring exerts the greater force on the
same on each
Two factors that greatly affect air resistance on falling objects are frontal area and
speed
Which of the following is not a vector quantity?
speed
While an iron block near Earth's surface is in free fall, it undergoes an increase in
speed
The circular path of a satellite orbiting Earth is characterized by a constant
speed, acceleration, and radial distance
A ring, a disk, and a solid sphere begin rolling down a hill together. Which reaches the bottom first?
sphere
The force of gravity acting on you will increase if you
stand on a planet with a radius that is shrinking
The force of gravity acting on you will increase if you
stand on a planet with a shrinking radius
Two planets in space gravitationally attract each other. If both the masses and distances are doubled, the force between them
stays the same
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
The rotational inertia of your leg is greater when your leg is
straight
When no forces act on a moving object their path is normally
straight-line
If the Sun were twice as massive
the pull of Earth on the Sun would double and its pull on Earth would double
Acceleration is defined as
the rate at which velocity itself changes
A black hole is
the remains of a giant star that has undergone gravitational collapse
A ball thrown upwards and returns to the same location. Compared with its initial speed its speed when it returns is about
the same
A force of 1 N accelerates 1-kg box at the rate of 1 m/s^2. The acceleration of a 2-kg box by a net force of 2 N is
the same
A rock dropped from a 5-m height, accelerates at 10 m/s^2 and strikes the ground 1 second later. If the rock is dropped from a height of 2.5 m, its acceleration of fall is
the same
Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is
the same
Burl and Paul paint signs together on a scaffold. Compared to their weights plus the weight of the scaffold, the sum of tensions in the supporting ropes is
the same
Compared to the mass of an apple on Earth, the mass of the apple on the Moon is
the same
Dr. Chuck projects a ball horizontally from a lab bench. If the projection speed of the ball were greater, the time in the air would be
the same
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 form the bench, the time in the air for Dr. Chuck's projected ball is
the same
Hang time is the time your feet are off the ground in a jump. If you jump upward inside a moving vehicle, your hang time will be
the same
If the Sun collapsed to a black hole, Earth's gravitational attraction to it would be
the same
You can safely stand on the overhanging end of a heavy plank that rests on a table. How much overhang depends on your mass and the plank's mass. If you can stand on the end of a plank that overhangs the edge of the supporting table 1/4 its total length, how massive is the plank compared to your mass?
the same
After rolling halfway down an incline, a marble's kinetic energy is
the same as its potential energy
A karate expert executes a swift blow and breaks 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 ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball when caught would be
the same as the speed it had when thrown upwards
After a rock thrown straight up reaches the top of its path and falls a short distance, its acceleration is (neglect air resistance)
the same at the top of its path
A car traveling at 100 km/h strikes an unfortunate bug and splatters it. The force of impact is
the same for both
The orbital path of a satellite has two focal points. When both focal points are together
the satellite path is a circle
A tiny gun made of strong buy very light material fires a bullet more massive than the gun itself. For such a weapon
the target would be safer than the shooter
A ball rolling down an incline has its maximum potential energy at
the top
Nellie tosses a ball upward at and angle. Assuming no air resistance, which component of velocity changes with time?
the vertical component
Which has more rotational inertia, a bicycle wheel or a solid disk of the same mass and diameter?
the wheel
A tin car whirled on the end of a string moves in a circle because
there is an inward force acting on the can
If you do work on a cart loaded with friends in one-third the usual time, you expend
three times the usual power
To kick a football so it won't topple end over end, kick it so the force of impact extends
through its center of gravity
To catch a fast-moving ball, you 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 on your hand principally because the
time of contact is increased
A heavy ball hangs by a string, with a second string attached to its bottom. A slow pull on the bottom string breaks the
top string
If Alex wishes to rotate his skateboard, then he must apply a
torque
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
twice
A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is
twice as much
A planet has half the mass of the Earth and half the radius. Compared to its weight on Earth, an apple on this planet would weigh
twice as much
Relative to an initial height, an object raised twice as high has a gravitational potential energy of
twice as much
The work you do when pushing a shopping cart twice as far while applying the same force is
twice as much
A 1000-kg car and a 2000-kg car are hoisted to the same height. Raising the more massive car requires
twice as much work
If you place a pipe over the end of a wrench when trying to rotate a stubborn bolt, efficiently making the wrench handle twice as long, you'll multiply the torque by
two
Consider two flywheels of the same size and shape, but one with twice the mass. Rotational inertia of the more massive one is
two times greater
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
Which of the following is a vector quantity?
velocity
Acceleration is defined as the CHANGE in
velocity divided by the time interval
As an object falls freely in a vacuum, its
velocity increases
While a car travels around a circular track at a constant speed, its
velocity is not zero
In comparison with other fundamental forces, the universal gravitational constant G indicates that gravity is
very weak
The Earth is closer to the Sun in January than in July, which accounts for the fact that the highest high tides in the Northern Hemisphere occur in
winter
Which has more rotational inertia, a girl running with her legs bent or the same girl running with her legs straight?
with straight legs
Your weight is the force
you exert against a supporting surface
Earth continually moves about 30 km/s through space, which means the wall you stand next to also is moving at 30 km/s. When you jump vertically the wall doesn't slam into you because
you're moving horizontally just as fast as the wall
