Physics Midterm
Two objects move apart from each other in space. As they move apart from each other, their velocities
decrease
An object travels 4 m in the 1st second of travel, 4 m again during the 2nd second of travel, and 4 m again during the 3rd second. Its acceleration is therefore
0 m/s2
A bullet fired horizontally hits the ground in 0.5 s. If it had been fired with half the speed in the same direction, it would have hit the ground in
0.5 s
The weight of 6 kg of salami is about
60 N
The scientist to first introduce the concept of mathematical models was
Galileo
A mack truck and a Volkswagen traveling at the same speed have a head- on collision. The vehicle to undergo the least change in velocity will be the
Mack truck
Suppose a gun were made of a strong but very light material. Suppose also that the pellet is more massive than the gun itself. For such a weapon
The larget would be safer than the shooter
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. Because of its inertia
The milk carton has no acceleration
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are included, the force required to keep the puck sliding at constant velocity is
Very small
When you stand at rest on a pair of bathroom scales, the readings on the scales will always
add to your weight
If an objects mass is increasing while a constant force is applied to the object, the accerleration
decreases
The power expended when a barbell is raised 2.0 m in 2 s is
dependent on the mass of the barbell
Newton did not discover
gravity
A ball is thrown upward and caught when it comes back down. Applying air resistance, the speed with which it is caught is
less than the speed it had when thrown upward.
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
Science and technology are
related to one another, but not the same thing
A scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is valid hypothesis, there must be a test for proving it.
right
Compared with the mass of a certain object on the moon, the mass of the same object on Earth
the same
A liter is a measure of an objects
volume
The muzzel velocity of a certain gun is 100 m/s. Neglecting air resistance, at the end of 1 s a bullet fired straight up into the air will have traveled a distance of about
95 m
In a scientific experiment, a control is
Both a test that duplicates an ecperimental test except for one variable and a way to study the effects of just one experimental variable
Which requires more work: lifting a 50-kg sack vertically 2 meters or lifting a 25-kg sack vertically 4 meters?
Both require the same amount of work
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 not to
Continue to follow a circular path
Compared with the force that brings a small car to a stop, the force required to bring a heavy truck traveling at the same speed to a stop.
Depends on the time involved
In science, facts
May change
Which has greater kinetic energy, a car traveling at 30 km/h or a car of half that mass traveling at 60 km/h?
The 60-km/h car
Your weight is
The gravitational attraction between you and the universe
The attraction of a persons body toward Earth is called weight. The other way of describing this force is
The pulling of a persons body towards Earth.
The force required to support an object in a gravitational field, is equal to
The weight of the object.
The synthesis of a large collection of information that contains wel-tested and verified hypotheses about certain aspects of the world is known as a scientific
Theory
Using science to analyze nature
adds depth to our understanding and therefore to our appreciation of nature
Which of the following involves passion, talent, and intelligence
all of these. art, literature, music, science
When a scientist is dishonest and reports false information, he or she
gets no second chance in the scientific community
As an object freely falls, its
velocity increases
A 10-N falling object encounters 6 N of air resistance. The magnitude of the net force on the object is
4 N
Starting from rest, the distance a freelt falling object will fall in 10 s is about
500 m
Which of the following is a scientific hypothesis
There are parts of the universe that will never be found by man.
A 1-kg chunk of putty moving at 1 m/s collides and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of
1 kgm/s
If a car increases its velocity from zero to 60 km/h in 5 seconds, its acceleration is
12 km/hs
Twenty seconds after starting from rest, a freely falling object on earth will have a speed of about
200 m/s
The average momentum of a 70-kg runner who covers 400 m in 500 s is
560 kgm/s
A car has a mass of 1000 kg and accelerates 1 m/s2. What is the magnitude of the force exerted on the car?
1000 N
If a rocket initially at rest accelerates at a rate of 25 m/s2 for one minute, its speed will be
1500 m/s
If a projectile is fired straght up at a speed of 20 m/s, the total time to return to its starting position is about
4 s.
earth's gravitational field
does not cancel inside earth
An object that has kinetic energy must be
moving
scientist repeat experimental findings in order to
neither imporve upon experimental design nor eliminate unseen errors
If a projectile is fired straight up at a speed of 20 m/s, the time it takes to reach the top of its path is about
2 s.
Most natural phenomena we wonder about
involve several scientific disciplines
A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. The average braking force is
2000 N
The scientific method is a method for
gaining new knowledge
A car traveling at 22 m/s comes to an abrupt halt in 0.2 s when it hits a tree. What is the deceleration in meters per second squared of the car?
110
When a car is braked to a stop, its kinetic energy is transformed to
heat
In each second of fall, the distance a freely falling object will fall is
increasing
A ball is thrown vertically into the air. Neglecting air resistance, its speed when it returns to its starting level compared to its inital speed is
the same
A ball is thrown vertically into the air. Neglecting air resistance, its time coming down compared to its time going up is
the same
A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. The recoil velocity of the rifle is about
1 m/s
The reason the moon pulls on the Earth, is that
The moon has mass.
Whenever the net force on an object is zero, its acceleration
is zero
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
Science is a body of knowledge that goes back to
Humankinds beginnings
A 30-kg girl and a 25-kg boy face each other on friction-free rollre blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girls speed is
.83 m/s
A ball is moving at 4 m/s and has a momentum of 48 kgm/s. What is the balls mass?
12 kg
If you exert 100 J in 50 s, your power output is
2 W
A stone is thrown horizontally from the top of a cliff. Two seconds after is has left your hand its vertical distance below the cliff is
20 m
A pot falls from a ledge and hits the ground two seconds later, the speed with which it hits the ground is about
20 m/s
A 2500-N pile driver ram falls 10 m and drives a post 0.1 m into the ground. The average impact force on the ram is
250,000 N
The average speed of a horse that gallops a distance of 10 km in a time of 20 min is
30 km/h
The two measurements necessary for calculating velocity are
Distance and time
The planet Jupiter is about 300 times as massive as Earth, yet on its surface you would weigh only about three times as much. This is because
Jupiter has about ten times Earths radius
A light object is dropped a second earlier, than a heavier object is dropped. The heavier object reaches the ground 10 m below
Later than the lighter object
The conservation of momentum is most closely related to
Newtons third law.
Each of us weighs a tiny bit less in a tunnel. The reason for this is the
The mass of the Earth above the tunnel
Which has the least mass
a king-size pillow
In science, a thoery is
a synthesis of a large body of well-tested knowledge
A rock thrown straight upward gets to the exact top of its path. A second later its velocity is
about 10 m/s and its acceleration is about 10 m/s2.
A package falls off a truck that is moving at 40 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is
about 40 m/s
Disregarding air resistance, objects fall with constant
acceleration
A feather and a coin dropped in a vacuum fall with equal
accelerations
A force is a pair because it has both
action and reaction counterparts
Science, art, and religion do not contradict one another because
all three have different domains
Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has
both increased time of impact and decreased impact force
When a rifle is fired, it recoils so both the bullet and rifle are set in motion. The rifle and bullet ideally acquire equal
but opposite amounts of momentum
Before a falling object has reached its terminal velocity, its acceleration is
constant
If the mass of Earth somehow decreases with no change in radius, your weight would
decrease
If the radius of earth somehow increased with no change in mass, your weight would
decrease
In science, an educated guess is a
hypothesis
In science, an educated guess is called a
hypothesis
Roll a bowling ball off the edge of a table. As it falls, Its vertical component of motion
increases
In each second of fall, the distance a freelt falling object will fall is
increasing
Aristole relied on ____ in explaining nature
logic
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.
Density is the ratio of
mass to volume
An ogject is placed 100 m from the moon. The ogject will fall toward the
moon
According to Newton, the lessor the distance between masses of interacting objects, the
more the gravitational force between them.
A rocket accelerates as it travels because
of its applied thrust
Of the sciences known as physics, chemistry, and biology, the most basic is
physics
A truly educated person is knowledgeable about
science, the arts, and religion. All of these.
The statement, "There are regions beneath Earths crust that will always be beyond the reach of scientific investigation is a
speculation
If experimental findings are not reproducible
the results are not considered vaild
