Physics Exam 1
Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
0
A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of
1 kg m/s
It takes 40 J to push a large box 4 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?
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 force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is
10 N
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.
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
A ball is moving at 3 m/s and has a momentum of 48 kg m/s. What is the ball's mass?
16 kg
A car moves 4 times as fast as another identical car. Compared to the slower car, the faster car has
16 times the KE
A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 150 km/hr?
180 m
A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. What is the jet's acceleration in meters per second per second when taking off?
2
Do 100 J of work in 50 s and your power output is
2 W
A 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at
2 m/s
A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is
20 km/h.
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
A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?
3 m/s
A girl 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 in meters per second per second?
3.0
A karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during this event is
3000 N
If a rocket initially at rest accelerates at a rate of 50 m/s 2 for one minute, its speed will be
3000 m/s.
A piece of rope is pulled by two people in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?
400 N
A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is
400 N.
An object is pulled northward by a force of 10 N and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is
5 N
Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed to do this job was
50 W
A person is attracted toward the center of Earth by a 500-N gravitational force. The Earth is attracted toward the person with a force of
500 N
If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is
6 km/h/s.
At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about
60 m/s
A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?
80 J
The scientist to first introduce the concept of inertia was
Galileo.
A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle that undergoes the greatest change in velocity will be the
Volkswagen
Which of the following has the largest momentum relative to the Earth's surface?
a pickup truck speeding along a highway
The mass of a pet turtle that weighs 10 N is
about 1 kg
When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is
about 1/10 as great
When you stand at rest on a pair of bathroom scales, the readings on the scales will always
add up to equal your weight
Hang from a pair of gym rings and the upward support forces of the rings will always
add up to equal your weight.
Your friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair - no wall, no tricks. You
agree that it can't be done
The force on an apple hitting the ground depends upon
all of these the time of impact with the ground the speed of the apple just before it hits whether or not the apple bounces.
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
all of these (mass, inertia, volume)
According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains
always have forces that oppose their motion.
A woman carries a heavy box across a room at a constant speed. How much work does she do on the box while walking?
ans: none More information is needed about the weight, distance, and her speed. More information is needed about the weight of the box.
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
When doing somersaults, you'll more easily rotate when your body is
balled up
Which would produce more force: driving into a very massive concrete wall with no "give," or having a head-on collision at the same speed with an identical car moving toward you with the same speed?
both the same
Arnold Strongman and Suzie Small each pull very hard on opposite ends of a massless rope in a tug-of-war. The greater force on the rope is exerted by
both the same, interestingly enough
If no external forces are acting on a moving object, it will
continue moving at the same velocity.
The two measurements necessary for calculating average speed are
distance and time.
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
doubled
According to the impulse-momentum equation Ft = change in (mv), a person will suffer less injury falling on a wooden floor which "gives" than on a more rigid cement floor. The "F" in the above equation stands for the force exerted on the
either the force on the person or the force on the floor
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is
equal to its weight
A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rock hits the floor
exactly below the midpoint of the ceiling.
The newton is a unit of
force
A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the
force that the ball exerts on the bat
A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. The reaction to this force is the
force the glove exerts on the ball
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to 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
An object following a straight-line path at constant speed
has zero acceleration.
A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force experienced by her hand is
identical to the force applied to the block
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
If one object has twice as much mass as another object, it also has twice as much
inertia
If your automobile runs out of fuel while you are driving, the engine stops but you do not come to an abrupt stop. The concept that most explains why is
inertia
For an action force, there must be a reaction force that
is exactly equal in magnitude
Whenever the net force on an object is zero, its acceleration
is zero
An object may have potential energy because of its
location
When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a
long time
A force is a vector quantity because it has both
magnitude and direction
A kilogram is a measure of an object's
mass
If an object has kinetic energy, then it also must have
momentum
Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater
momentum
A large metal ball is shot from a cannon with a short barrel. If the same ball were to be shot from cannon with a longer barrel, its muzzle velocity would be
more
An object that has kinetic energy must be
moving
Horses that move with the fastest linear speed on a merry-go-round are located
near the outside
If you push for a half hour or a whole hour against a stationary wall
no work on the wall is done in either case
A skydiver falls towards the Earth. The attraction of the Earth on the diver pulls the diver down. What is the reaction to this force?
none of these air resistance the diver encounters while falling the attraction to the planets, stars, and every particle in the universe water resistance that will soon act upward on the diver
A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of
power
As a ball falls, the action force is the pull of Earth on the ball. The reaction force is the
pull of the ball's mass on the Earth
A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because the
rifle has much more mass than the bullet
The force exerted on the tires of a car to directly accelerate it along a road is exerted by the
road
Compared to 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
Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr?
the 60 km/hr car
It is correct to say that impulse is equal to
the change in momentum it produces
Your weight is
the gravitational attraction force between you and the Earth.
A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first?
the light woman
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that
the milk carton has inertia
The attraction of a person's body toward Earth is called weight. The reaction to this force is
the person's body pulling on the Earth
Compared to the mass of a certain object on Earth, the mass of the same object on the moon is
the same
A automobile and a baby carriage traveling at the same speed collide head-on. The impact force is
the same for both
A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is
the same for both
Earth pulls on the moon. Similarly the moon pulls on Earth, evidence that
these two pulls comprise an action-reaction pair
If you do work on an object in one-third the usual time, your power output is
three times the usual power output
To catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride 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
Two identical arrows, one with twice the kinetic energy of the other, are fired into a hay bale. The faster arrow will penetrate
twice as far as the slower arrow
An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be
twice as much
If an object is raised twice as high, its potential energy will be
twice as much
A 1000-kg car and a 2000-kg car are hoisted the same distance. Raising the more massive car requires
twice as much work
If you push an object a given distance, while applying twice the force, you do
twice as much work
If you push an object twice as far while applying the same force, you do
twice as much work
If you find that twice as much work is needed to perform a task but it takes twice as much time, the amount of power required is
unchanged
While an object near the Earth's surface is in free fall, its
velocity increases
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is
zero
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 at constant velocity is
zero
When a falling object has reached its terminal velocity, its acceleration is
zero
