PHYSICS

A projectile is fired horizontally in a region of no air resistance. The projectile maintains its horizontal component of velocity because

it is not acted on by any horizontal forces.

A pair of tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the

lead-filled ball.

Which has the greatest number of protons in its nucleus?

lead.

A ball thrown straight upward takes 10 seconds to go up and return to the ground. Because of air resistance, the time taken for the ball just to go up is

less than 5 s.

A 1-kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about

more than 2.0 J.

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.

A ball rolling down an incline has its minimum speed

near the top of the incline.

If two protons are added to an oxygen nucleus, the result is

neon

Which of the following are electrically neutral?

neutron

In an electrically neutral atom, the number of protons in the nucleus is balanced by an equal number of

orbital electrons.

If a strong wind from the west breaks a window in the north wall of a house, most of the glass will fall

outside the house.

Of the sciences known as physics, chemistry, and biology, the most basic is

physics

In science, an educated guess is called a

hypothesis

If a non-rotating object has no acceleration, then we can say for certain that it is

in mechanical equilibrium.

The direction of a gravitational field is

in the same direction as the gravitational attraction.

If one object has twice as much mass as another object, it also has twice as much

inertia

Most natural phenomena we wonder about

involve several scientific disciplines.

A bullet is dropped into a river from a very high bridge. At the same time, another bullet is fired from a gun, straight down towards the water. Neglecting air resistance, the acceleration just before striking the water

is the same for each bullet.

A ball is projected 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.

The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is

10 N.

A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with

10 times as much force.

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, two seconds later the rock's speed is

14.7 m/s.

A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time?

300 m

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 car accelerates from rest for 5 seconds until it reaches a speed of 20 m/s. What is the car's acceleration in meters per second per second?

4

Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration in meters per second per second?

40

Suppose a miracle car has a 100% efficient engine and burns fuel that has a 40-megajoules-per-liter energy content. If the air drag and overall frictional forces on this car traveling at highway speeds total 1000 N, what is the overall limit in distance per liter it could be driven on the highway?

40 km

A vehicle that weighs 4000 N on the surface of the Earth is travelling in outer space at a speed of 200 m/s. The smallest constant force that must be applied to stop it in 20 seconds is

4000 N.

A person is attracted toward the center of the Earth by a 500-N gravitational force. The Earth is attracted toward the person with a force of

500 N.

When a woman stands at rest with both feet on a scale, it reads 500 N. When she gently lifts one foot, the scale reads

500 N.

The change in momentum, in kg m/s, that occurs when a 1.0 kg ball travelling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s is

6

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

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is

6 km/h /s.

A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s . It can be stopped by applying a constant force of 20 N for

800 seconds.

If you drop an object, it will accelerate downward at a rate of 9.8 meters per second per second. If you instead throw it downwards, its acceleration (in the absence of air resistance) will be

9.8 meters per second per second.

The planet Jupiter is about 300 times as massive as Earth, yet on its surface you would weigh only about 3 times as much. This is because

Jupiter's radius is 10 times the Earth's radius.

A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same location. Neglecting air resistance, the acceleration of

each bullet is 9.8 meters per second per second.

An object is placed exactly halfway between the Earth and moon. The object will fall toward the

earth

The Bernoulli effect causes passing ships to be drawn together when the ships are close and moving in

either the same or opposite directions.

A force that determines the chemical properties of an atom is a

electrical force.

The chemical properties of matter come mostly from its

electrons

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gases.

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.

The scientific method is a method for

gaining new knowledge.

When a scientist is dishonest and reports false information, he or she

gets no second chance in the scientific community.

When carbon and oxygen atoms combine, energy is

given off by the reaction.

Momentum is transferred to the ground when an apple falls on it. The momentum absorbed by the ground is

greater than that of the apple only if the apple bounces.

An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration

halves

An object following a straight-line path at constant speed

has zero acceleration.

A skydiver's terminal velocity will be greatest if she falls

head first.

In our part of the universe, antimatter is

short-lived.

Assuming all the atoms exhaled by Julius Caesar in his last dying breath are still in the atmosphere, then we probably breathe one of those atoms with each

single breath.

Which requires the most amount of work by the brakes of a car?

slowing down from 100 km/h to 70 km/h

The statement, "There are regions beneath Earth's crust that will always be beyond the reach of scientific investigation," is a

speculation

A factor that usually determines whether a substance is in the solid, liquid, gaseous, or plasma state is its

temperature

What makes an element distinct?

the number of protons

The ball rolling down an incline has its maximum potential energy at

the top

The Earth pulls on the moon. Similarly the moon pulls on the Earth, evidence that

these two pulls comprise an action-reaction pair.

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.

If you push an object a given distance, while applying twice the force, you do

twice as much work.

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.

Which of these atoms has the greatest amount of electrical charge in its nucleus?

uranium

Atmospheric pressure is caused by the

weight of the atmosphere.

The force required to maintain an object at a constant velocity in free space is equal to

zero

If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about

2 seconds.

If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about

2 seconds.

In drinking soda or water through a straw, we make use of

atmospheric pressure.

If two protons are removed from an oxygen nucleus, the result is

carbon

A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration

decreases

Compared to the mass of a certain object on Earth, the mass of the same object on the moon is

the same

Compared to the atoms that make up the body of an elderly person, the atoms that make up the body of a newborn baby are

the same age.

Drop a rock from a 5-m height and it accelerates at 10 m/s 2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is about

the same amount.

After rolling halfway down an incline a marble's kinetic energy is

the same as its potential energy.

A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is always

the same as the speed it had when thrown upwards.

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.

A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s 2. The acceleration of a mass of 2 kg acted upon by a net force of 2 N 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.

In science, a theory is

a synthesis of a large body of well-tested knowledge.

In each second of fall, the distance a freely falling object will fall is

about 5 m.

The human body can, under certain conditions, withstand an acceleration of 10 g. What net force would produce this acceleration of a 50-kg person?

about 5000 N

If several balls are thrown straight up with varying initial velocities, the quantity that will have the same value for each trial is the ball's

acceleration

Whereas impulse involves the time that a force acts, work involves the

distance that a force acts.

A car traveling at 22 m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration in meters per second per second of the car?

220

A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is

almost equal to its weight.

Compared to the mass of a hydrogen atom, the mass of an oxygen atom is

16 times as great.

A bullet fired horizontally from a rifle begins to fall

as soon as it leaves the barrel.

An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car's speed

decreases

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 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 in meters per second per second is

0

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 net recoil will be

0

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second , and 8 meters again during the third second. Its acceleration in meters per second per second is approximately

0.

A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is

1

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is

1 N

A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 0.01 kg at a speed of 200 m/s. The recoil velocity of the rifle is about

1 m/s.

Airplane flight best illustrates

Bernoulli's principle.

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

Both hit at the same time.

Which of these statements is true?

Molecules are the smallest subdivision of matter that still retains chemical properties of a substance.

Compared to the recoiling rifle, the bullet fired has

a greater kinetic energy.