CP Physics- Mid-Term Review
If your car runs out of gas, why can't you push on the car's windshield from the inside to move it?
In order for the car to move, a force must be exerted by the car on the ground
The unit of work is the
Joule
An archer shoots an arrow. Consider the action force to be the bowstring against the arrow. The reaction to this force is the
arrow's push against the bowstring
If a weight scale shows that you weigh 200 kg on the surface of the Earth, and then you skydive with both of your feet attached to the scale, you will read a weight of
0kg
A pencil lies on your desk. If the earth is moving around the sun at a speed of 30 km/s, how fast is the pencil moving relative to the desk?How fast is the pencil moving relative to the sun
0km/s; 30km/s
What is the resultant of a 3 unit vector and 4 unit vector at right angles to each other
5 units
A 2-kg ball is thrown at 3 m/s. What is the ball's momentum?
6 kg.m/s
A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car's average acceleration?
6 m/s2
If a projectile is fired straight up at a speed of 30 m/s, the total time to return to its starting point is about
6 seconds
Suppose you take a trip that covers 180 km and takes 3 hours to make. Your average speed is
60 km/h
As a 600-N woman sits on the floor, the floor exerts a force on her of
600N
How much power is expended if you lift a 60 N crate 10 meters in 1 second?
600W
A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 60m/s, where will the cannonball be 1 second later?
60m downrange
A freely falling object starts from rest. After falling for 6s, it will have a speed of about
60m/s
Which best approximates the resultant of a pair of 6-unit vectors at right angles to each other?
8 units
Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.
always true
The ratio of useful work output to total work input is called the
efficiency
A table tennis ball moving forward with 5 units of momentum strikes and bounces backwards 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 5 units
A scalar is a quantity that has
magnitude
If the force of gravity suddenly stopped acting on the planets, they would
move in straight lines tangent to their orbits
An object that has kinetic energy must be
moving
Nellie Newton holds an apple in her hand. If action is Earth pulling on the apple, then reaction is
neither A nor B
A small economy car (low mass) and a limousine (high mass) are pushed from rest across a parking lot, equal distances with equal forces. The car that receives more kinetic energy is the
neither one-they receive the same amount of kinetic energy
Which has more mass, a kilogram of feathers or a kilogram of iron?
neither the both have the same mass
If Kelly the skaters speed increases so he has three time the momentum, then his kinetic energy increases by
nine times
Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is moving horizontally, Jose can jump
no higher
A rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket is the force
of the exhaust gases on the rocket
A high school student hits a nail with a hammer. During the collision there is a force
on the nail and also on the hammer
Kinetic energy of an object is equal to
one half the product of its mass times its speed squared
Friction is a force that always acts
opposite to an object's motion
A table tennis ball launcher is fired. Compared to the force on the ball, the impulse on the launcher is
the same
An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the force of the bug on the car is
the same
Aunt Minnie throws a rock downward, and air resistance is negligible. Compared to a rock that is dropped, the acceleration of the rock after it is thrown is
the same
Compared to its mass on Earth, the mass of a 10-kg object on the moon is
the same
The momentum of an object is defined as the objects
mass times its velocity
The ratio of output force to input force of a simple machine is called the
mechanical advantage
An object that has kinetic energy must have
momentum
If an object has kinetic energy, then it also must have
momentum
If the velocity of a moving object doubles, then what else doubles?
momentum
An airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is
more
If you were to weigh yourself in an elevator that is accelerating upward, compared to your ordinary weight you would weigh
more
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
A large truck and a small car traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be
the small car
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. Which ball has the greater force acting on it?
the steel ball
Suppose a cannon is made of a strong but very light material. Suppose also that the cannonball is more massive than the cannon itself. For such a system
the target would be a safer place than where the operator is located
In order to find the components of a vector, you should
all of the above
In order to increase the final momentum of a golf ball, we could
all of the above
One possible unit of speed is
all of the above
The acceleration produced by a net force on an object is
all of the above
The force of an apple hitting the ground depends upon
all of the above
Forces always occur
in pairs
The reason padded dashboards are used in cars is that they
increase the time of impact in a collision
A block is at rest on an incline. the force of friction necessary to prevent the block form sliding increases when the incline angle is
increased
When a car's speed triples, its kinetic energy
increases by nine times
One object has twice as much mass as another object. The first object also has twice as much
inertia
When you look at the speedometer in a moving car, you can see the car's
instantaneous speed
How does acceleration of an object change in relation to its mass? It is
inversely proportional
When a basketball player jumps to make a shot, once the feet are off the floor, the jumper's acceleration
is g; no more, no less
Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?
it halves
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is
its weight
An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is
larger
Compared to its weight on Earth, a 10-kg object on the moon will weigh
less
The hang time (time one's feet are off the ground in a jump) for most athletes is
less than 1 second
A ball thrown into the air with 100J 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 100J
A small economy car (low mass) and a limousine (high mass) are pushed from rest across a parking lot, equal distances with equal forces. The car that receives the greater impulse is the
limousine
Potential energy is the energy an object has because of its
location
A 6-N falling object encounters 6N of air resistance. The magnitude of the net force on the object is
0N
You use a pulley to lift your bike to the ceiling for winter storage. When you bought the pulley, the salesman claimed that the pulley has a mechanical advantage of 10. While lifting the bike, you notice that the pulley is squeaking because it has rusted over the summer. You determine that the pulley now has an actual mechanical advantage of 3. What is its efficiency?
.3
While using a simple 2-piston hydraulic system, you apply a force of 10 N on the first piston to push it down 1 meter. You watch the second piston move a 100 N crate up a distance of 5 centimeters. What is the efficiency of the hydraulic system?
.50
A ball is thrown straight up. At the top of its path its instantaneous speed is
0 m/s
A train travels 6 meters in the first second of travel, 6 meters again during the second second of travel and 6 meters again during the third second. Its acceleration is
0 m/s2
How much work is done on a 60-N box of books that you carry horizontally across a 6-m room?
0J
The vertical height attained by a basketball player who achieves a hang time of a full one second is about
1.2m
If a truck has ten times the mass of a car and the two vehicles are pushed with an equal force, you would expect the acceleration of the truck to be
1/10 times that of the car
A woman can lift barrels a vertical distance of 1 meter or can roll them up a 2-meter long ramp to the same elevation. If she uses the ramp, the applied force required is
1/2 as much
If shopping cart A has five times more mass in it than shopping cart B and the two carts are pushed with equal forces, you can expect the acceleration of shopping cart A to be
1/5 times that of shopping cart B
A freely falling object starts from rest. After falling for 1s, it will have a speed of about
10 m/s
A car accelerates at 2 m/s2. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 20 m/s?
10 seconds
It takes 80 J to push a large box 8 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?
10N
The mass of a lamb that weighs 110 N is about
11 kg
Suppose a moving car has 3000 J of kinetic energy. If the car's speed doubles, how much kinetic energy will it then have?
12000J
A box is dragged without acceleration in a straight line path across a level surface by a force of 13N. What is the frictional force between the box and the surface
13N
A person on a roof throws one ball downward and an identical ball upward at the same speed. The ball thrown downward hits the ground with 140J of kinetic energy. Ignoring air friction, with how much kinetic energy does the second ball hit the ground?
140J
A 20-N falling object encounters 4N of air resistance. The magnitude of the net force on the object is
16N
A 1-N apple falls to the ground. The apple hits the ground with an impact force of
1N
And Apple weighs 1 N. The net force on the Apple when it is in freefall is
1N
A girl pulls on a 10-kg wagon with a constant force of 20N. What is the wagon's acceleration?
2 m/s2
A jet has a mass of 40000kg. The thrust for each of four engines is 20000N. What is the jets acceleration when taking off?
2 m/s2
A piece of putty moving with 2 units of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both are set in motion with a combined momentum that is
2 units
A tow truck exerts a force of 2000N on a car, accelerating it at 1m/s2. What is the mass of the car?
2000kg
If a ball were equipped with a speedometer and allowed to fall freely on a planet where the acceleration due to gravity is 23 m/s2, the reading on the speedometer would increase each second by
23 m/s
Suppose a car is moving in a straight line and steadily increases its speed. It moves from 35 km/h to 40 km/h the first second and from 40 km/h to 45 km/h the next second. What is the car's acceleration?
5 km/h.s
Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is
25N
About how efficient is a typical gasoline-burning car engine?
30%
A 60-N object moves at 1 m/s. Its kinetic energy is
3J
A ball is moving at 6.0m/s and has a momentum of 24.0 kg.m/s. What is the ball's mass?
4.0kg
Two people pull on a rope in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?
400N
How much work is done on a 20-N crate that you lift 2 m?
40J
A person is attracted towards the center of Earth by a 440-N gravitational force. The force with which Earth is attracted toward the person is
440N
You pull horizontally on a 50 kg crate with a force of 450 N and the friction force on the crate is 250 N. The acceleration of the crate is
4m/s2
A 4.0-kg ball has a momentum of 20.0 kg.m/s. What is the ball's speed?
5.0m/s
A 5.0-kg chunk of putty moving at 10.0 m/s collides with and sticks to a 7.0-kg bowling ball that is initially at rest. The bowling ball with its putty passenger will then be set in motion with a momentum of
50.0 kg.m/s
A jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 50000N. How much air resistance acts on the jet?
50000N
A woman weighing 550 N sits on the floor. She exerts a force on the floor of
550N
Suppose a jumper claims a hang time of 2 seconds. Then that jumper must be able to jump a vertical distance of
5m
Suppose two people, one having three times the mass of the other, pull on opposite sides of a 20-meter rope while on frictionless ice. After a brief time, they meet. The more massive person slides a distance of
5m
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 frictionless inclined plane is 8.0m long and rests on a wall that is 2.0m high. How much force is needed to push a block of ice weighing 300.0N up the plane?
75.0N
A sportscar has a mass of 1500 kg and accelerates at 5 meters per second squared. What is the magnitude of the force acting on the sportscar
7500N
How many joules of work are done on a box when a force of 25 N pushes it 3 m?
75J
How much power is required to do 40 J of work on an object in 5 seconds?
8W
Which of the following has the largest momentum
A pickup truck traveling down the highway
Energy is changed from one form to another with no net loss or gain
Always true
If you stand on a weight scale in an elevator that is accelerating upwards, why do you observe an increase in your weight
Because you are accelerating upwards there is more compression of the springs of the scale. The weight reading on the scale reflects the amount of compression of the springs
A ball thrown in the air will never go as far as physics ideally would predict because
air friction slows the ball
If all people, animals, trains and trucks all over the world began to walk or run towards the east, then
Earth would spin a bit slower
How much farther will a car traveling at 100 km/s skid than the same car traveling at 50 km/s?
Four times as far
At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
Neither- they both hit the ground at the same time
You and a friend are jumping on a trampoline. Why does Earth, which is rapidly orbiting around the sun, not move under your feet when you jump?
Newton's first law holds that your body moves along with earth because it is not compelled to change its motion by an unbalanced force
Superman is at rest in space when he throws an asteroid that has more mass than he does. Which moves faster, Superman or the asteroid?
Superman
Which has greater kinetic energy, a car traveling at 330 km/h or a half-as-massive car traveling at 60 km/h?
The 60km/h car
Suppose you accidentally drive into a tree. Which of the following correctly describes the interaction between your car and the tree?
The car and the tree mutually exert equal and opposite forces on each other
If you exert a force of 12000N on a 3000kg car and a 6000kg truck that are both originally at rest, what will be the resulting accelerations of the objects?
The car will accelerate at 4 m/s2 and the truck will accelerate 2m/s2
If you drop a feather and a coin at the same time in a tube filled with air, which will reach the bottom of the tube first?
The coin
Acceleration is defined as
the rate at which velocity itself changes
You drive past a farm, and you see a cow pulling a plow to till a field. You have just learned about Newton's third law, and you wonder how the cow is able to move forward if the plow is exerting an equal and opposite force on the cow. Which of the following explains the movement of the cow and plow?
The force exerted by the cow on the plow is smaller than the force that the cow exerts on the ground to move forward
A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?
The force of the ball against the bat
A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?
The force the glove exerts on the ball
Which has more momentum, a large truck moving at 30 miles per hour or a small truck moving at 30 miles per hour?
The large truck
An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass?
The one on the moon
As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?
The pull of the ball's mass on Earth
A piece of putty and a rubber ball have the same mass. If you drop them from the same height, which object will produce a greater impulse and why?
The rubber ball will produce a greater impulse because it will bounce
A car traveling along the highway needs a certain amount of force exerted on it to stop. More stopping force may be required when the car has
all of the above
A collision is considered elastic if
all of the above
A truck travels north with a momentum of 2600 kg.km/s and a motorcycle heads west with a momentum of 1500 kg.km/s. The motorcycle hits the truck. If the two vehicles collide then stick together, what is the momentum and direction of travel
The vehicles travel with a momentum of 3000 kg.km/s in the NW direction
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration?
They both have the same acceleration
Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?
To nearly its original height
The unit of power is the
Watt
Suppose you are in a car that is going around a curve. The speedometer reads a constant 30mph. Which of the following is NOT true?
Your velocity is constant
Suppose an object is in free fall. Each second the object falls
a larger distance than in the second before
A karate expert executes a swift blow and splits a cement block with her bare hand
all of the above
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by
about 10 m/s
When something falls to the ground, it accelerates. This acceleration is called the acceleration due to gravity and is symbolized by the letter g. What is the value of g on earths surface?
about 10 m/s2
When you jump off a step, you usually bend your knees as you reach the ground. By doing this, the time of the impact is about 10 times more what it would be in a stiff-legged landing, and the average force on your body is reduced by
about 10 times
An object has a constant mass. A constant force on the object produces constant
acceleration
In the absence of air resistance, objects fall at constant
acceleration
If the momentum of an object changes and its mass remains constant
all of the above
A table tennis ball launcher is fired. Compared to the force on the ball, the force on the launcher is
the same
Earth pulls on the moon. and similarly the moon pulls on the earth. This is evidence that the
both a and b
Mechanical energy can be in the form of
both kinetic and potential energy
The law of inertia applies to
both moving and nonmoving objects
Bronco the skydiver falls toward earth. The attraction of earth on bronco pulls him down. The reaction to this force is
bronco pulling up on earth
A cannon recoils from launching a cannonball. The speed of the cannon's recoil is small because the
cannon has far more mass than the cannonball
Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle
continues at the speed it had when it encountered the second force
When the angle of an incline with a block resting on it increases, the normal support force
decrases
You are on a frozen pond, and the ice starts to crack. If you lie down on the ice and begin to crawl, this will
decrease the pressure on the ice
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
A popular toy consists of an aligned row of identical elastic balls suspended by strings so they touch each other. When two balls on one end and elevated and released, they slam into the array of balls and two balls pop out on the other side. If instead, one ball popped out with twice the speed, this would be a violation of the conservation of
energy
An object at rest may have
energy
In physics, work is defined as
force times distance
Accelerations are produced by
forces
According to newtons third law if you push gently on something it will push
gently on you
Consider drops of water leaking from a water faucet. As the drops fall they
get farther apart
An object following a straight-line path at constant speed
has zero acceleration
while roller-skating, granny collides with her tiny grandson Ambrose who is at rest. Ignoring any friction effects, Ambrose's speed after the collision will be greatest when
he and granny make a bouncing collision, each is going in opposite directions
Consider molecules of hydrogen gas and molecules of heavier oxygen gas that have the same kinetic energy. The molecules with the greater speed are
hydrogen
A cannon fires a cannonball. The speed of the cannonball will be the same as the speed of the recoiling cannon
if the mass of the cannonball equals the mass of the cannon
A cannonball shot from a long-barrel cannon travels faster than one shot from a short-barrel cannon because the cannonball receives a greater
impulse
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of
power
The astronomer copernicus publicly stated in the 1500s that earth
revolves around the sun
A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
road
A meteor that originally was heading south breaks up into two chunks . One of the chunks moves southwest. The second chunk was not immediately found but scientists guessed that they should look for an object heading
southeast
Suppose an astronaut in outer space wishes to toss a ball against a very massive and perfectly elastic concrete wall and catch it as it bounces back. If the ball is as massive as the astronaut, then
the astronaut will never catch the first bounce
The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that
the ball with the larger force also has the larger mass
The force that accelerates a rocket into outer space is exerted on the rocket by
the exhaust gases
A heavy person and a light person parachute together and wear the same size parachutes. Assuming they open their parachutes at the same time, which person reaches the ground first?
the heavy person
A sheet of paper can be withdrawn form under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
the milk carton has inertia
You would have the largest mass of gold if your chunk of gold weighed 1 N on
the moon
In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because
the time of impact is increased
The amount of potential energy possessed by an elevated object is equal to
the work done in lifting it
Momentum of a system is conserved only when
there is no net external force acting on the system
Suppose a girl is standing on a pond where there is no friction between her feet and the ice. In order to get off the ice, she can
throw something in the direction opposite to the way she wants to go
Acceleration is defined as the CHANGE in
velocity divided by the time interval
As an object falls freely in a vacuum, its
velocity increases
Which of the following is NOT true about Aristotle's concept of violent motion
violent motion is thought to be either straight up or straight down
The law of inertia states that an object
will do all of the above
A push on a 1-kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push
with 10 times as much force
Power is defined as the
work done on an object divided by the time taken to do the work
All simple machines ideally work on the principle that
work input equals work output
If a horse pulls on a wagon at rest, the wagon pulls back equally on the horse. Can the wagon be set into motion?
yes, because ether is a net force acting on the wagon
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 you throw a heavy ball while standing on roller skates. If instead you go through the motions of throwing the ball but hold onto it, your net recoil velocity will be
zero
The force required to maintain an object at a constant speed in free space is equal to
zero
Two gliders having the same mass and speed move toward each other on an air track and stick together. After the collision, the velocity of the gliders is
zero
