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A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly.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