PHYS Exam 1

What is/are the reason(s) that scientists use an ellipse rather than a circle as a model of the planetary orbits a) the elliptical model can be used to relate the variations in the speed of the planet with its distance from the sun b) predictions of the position of a planet are more accurate when calculated from the elliptical model c) the elliptical model can better explain the periodic variations in the distance of each planet from the sun d) all of the above

d) all of the above

a scientific law or theory is valid a) forever b) for a certain number of years, after which it is retested c) as long as a committee of scientists says so d) as long as it is not contradicted by new experimental findings

d) as long as it is not contradicted by new experimental findings

The centripetal force that keeps the earth in its orbit around the sun is provided by a) by inertia b) by the earths rotation on its axis c) partly by the gravitational pull of the sun d) entirely by the gravitational pull of the sun

d) entirely by the gravitational pull of the sun

The law of gravity a) applies only to large bodies such as planets and stars b) accounts for all known forces c) holds only in the solar system d) holds everywhere in the universe

d) holds everywhere in the universe

Newton's first law of motion deals with a) force b) acceleration c) weight d) inertia

d) inertia

Astrology a) provides a scientific basis for planning our lives. b) correctly predicts the future. c) is based on the scientific method. d) is nonsense.

d) is nonsense

If the earth were 3 times as far from the sun as it is now, the gravitational force exerted on it by the sun would be a) 3 times as large as it is now b) 9 times as large as it is now c) one-third as large as it is now d) one-ninth as large as it is now

d) one-ninth as large as it is now

A car rounds a curve at 20 km/h. If it rounds the curve at 40 km/h, its tendency to overturn is a) halved b) doubled c) tripled d) quadrupled

d) quadrupled

On a rainy day the maximum frictional force between a car's tires and a certain level road surface is reduced to half its usual value. The maximum safe speed for rounding a curve is a) unchanged. b) reduced to 25% of its usual value. c) reduced to 50% of its usual value. d) reduced to 71% of its usual value.

d) reduced to 71% of its usual value.

When a boy pulls a cart, the force that causes him to move forward is a) the force the cart exerts on him b) the fore he exerts on the cart c) the force he exerts on the ground with his feet d) the force the ground exerts on his feet

d) the force the ground exerts on his feet

How does the sun's gravitational force on the earth change throughout the year? a) the gravitational force of the sun on the earth is constant throughout the year b) the gravitational pull is less when it is spring or fall in the Northern hemisphere c) the gravitational pull is greater when it is summer in the Northern hemisphere d) the gravitational pull is greater when it is winter in the Northern hemisphere

d) the gravitational pull is greater when it is winter in the Northern hemisphere

Leap years are not needed because a) the earth's orbit is not a perfect circle b) the length of the day varies c) the length of the year varies d) the length of the year is not a whole number of days

d) the length of the year is not a whole number of days

The acceleration of a certain moving object is constant in magnitude and direction. Which statement must be true? a) the path of the object is backward in a straight line b) the path of the object is forward in a straight line c) the path of the object is circular d) the path of the object may be in any of these directions

d) the path of the object may be in any of these directions

Compared with her mass and weight on the earth, an astronaut on Venus, where the acceleration of gravity is 8.8 m/s^2, has a) less mass and less weight b) less mass and the same weight c) less mass and more weight d) the same mass and less weight

d) the same mass and less weight

which one or more of the following sets of displacements might be able to return a car to its starting point? a) 5, 5, and 5 km b) 5, 5, and 10 km c) 5, 10, and 10 km d) 5, 5, and 20 km

a b and c

The measurements of a room are given as length = 5.28 m and width = 3.1 m. Since (5.28)(3.1) = 16.368, the rooms area is correctly expressed as a) 16 m^2 b)16.0 m^2 c) 16.4 m^2 d) 16.368 m^2

a) 16 m^2

Arrange the following planets in the order of their distance from the sun. 1. Venus 2. Mars 3. Earth 4. Mercury a) 4, 1, 3, 2 b) 1, 4, 3, 2 c) 2, 3, 1, 4 d) 3, 2, 4, 1

a) 4, 1, 3, 2

the object in the sky that apparently moves least in the course of time is a) Polaris b) Venus c) the sun d) the moon

a) Polaris

Scalar quantities require only a number and a unit to be completely specified. a) True b) False

a) True

the "scientific method" is a) a continuing process b) a way to arrive at ultimate truth c) a laboratory technique d) based on accepted laws and theories

a) a continuing process

A hypothesis is a) a new scientific idea b) a scientific idea that has been confirmed by further experiment and observation c) a scientific idea that had been discarded because it disagrees with further experiment and observation d) a group of linked scientific ideas

a) a new scientific idea

Kepler modified the Copernican system by showing that the planetary orbits are a) ellipses b) circles c) combinations of circles forming looped orbits d) the same distance apart from one another

a) ellipses

A car that is towing a trailer is accelerating on a level road. The magnitude of the force the car exerts on the trailer is a) equal to the force the trailer exerts on the car b) greater than the force the trailer exerts on the car c) equal to the force the trailer exerts on the car d) equal to the force the road exerts on the trailer

a) equal to the force the trailer exerts on the car

When first proposed, a scientific idea is usually called a: a) hypothesis. b) law. c) theory. d) model.

a) hypothesis

the ongoing evolution of living things a) is one of the basic concepts of biology b) is one of the basic concepts of "intelligent design" c) has no basis in observation d) is in conflict with all religions

a) is one of the basic concepts of biology

The earth bulges slightly at the equator and is flattened at the poles because a) it spins on its axis b) it revolves around the sun c) of the sun's gravitational pull d) of the moon's gravitational pull

a) it spins on its axis

Which of the following units could be associated with a vector quantity? a) km/s2 b) kg/s c) hours d) m3

a) km/s2

An object is moving in a circle with a constant speed. Its acceleration is constant in a) magnitude only b) direction only c) both magnitude and direction d) neither magnitude nor direction

a) magnitude only

The speed needed to put a satellite in orbit does not depend on a) the mass of the satellite b) the radius of the orbit c) the shape of the orbit d) the value of g at the orbit

a) the mass of the satellite

Which of the following is no longer considered valid? a) the ptolemaic system b) the copernican system c) Kepler's laws of planetary motion d) Newton's law of gravity

a) the ptolemaic system

A year is the time needed for: a) the sun to migrate completely around the sky. b) the moon to migrate completely around the sky. c) the earth to turn completely on its axis. d) None of the choices are correct.

a) the sun to migrate completely around the sky.

Of the following, the shortest is a) 1 mm b) 0.01 in. c) 0.001 m d) 0.001 ft

b) 0.01 in.

A centimeter is a) 0.001 m b) 0.01 m c) 0.1 m d) 10 m

b) 0.01 m

A car that starts from rest with a constant acceleration travels 50 m in the first 5 s. The car's acceleration is a) 2 m/s2. b) 4 m/s2. c) 10 m/s2. d) 20 m/s2

b) 4 m/s2.

Ancient astronomers were troubled by variations in the brightness of the planets with time. Does the ptolemaic or the copernican model better account for these variations? why? a) Ptolemaic. If the earth were at the center ofthe orbits of the planets they would vary in the distance relative to the earth b) Copernican. If the earth and the other planets have concentric orbits around the sun, their distance from one another would vary c) Neither copernican nor ptolemaic, only Kepler's model could account for this phenomena

b) Copernican. If the earth and the other planets have concentric orbits around the sun, their distance from one another would vary

Speed is an example of a vector quantity. a) True b) False

b) False

The force that has to be applied to an object to make it move in a curved path is called centrifugal force. a) True b) False

b) False

Which statement about a pair of units is true? a) a mile is shorter than a kilometer b) a yard is shorter than a meter c) an inch is shorter than a centimeter d) a foot is shorter than a centimeter

b) a yard is shorter than a meter

The sun, moon, and planets all follow approximately the same path from east to west across the sky. What does this suggest about the arrangement and movement of these members of the solar system? a) all planets move in the same direction around the sun b) all of these are correct c) each of these objects is moving relative to the earth d) the orbit of each planet lies in or near the plane of the earth's equator

b) all of these are correct

a constellation is a) an especially brighter star b) an apparent pattern of stars in the sky c) a group of stars close together in space d)a group of planets close together in space

b) an apparent pattern of stars in the sky

The weight of an object is a) the same everywhere on the earth's surface. b) greater at the poles than at the equator. c) less at the poles than at the equator. d) Any of these choices, depending on the phase of the moon.

b) greater at the poles than at the equator

The speed of a planet in its orbit around the sun a) is constant b) is highest when the planet is closest to the sun c) is lowest when the planet is closest to the sun d) varies, but not with respect to the planets distance from the sun

b) is highest when the planet is closest to the sun

The weight of an object a) is the quantity of matter it ontains b) is the force with which it is attracted to the earth c) is basically the same quantity as its mass but is expressed in different units d) refers to its inertia

b) is the force with which it is attracted to the earth

The gravitational force with which the earth attracts the moon a) is less than the force with which the moon attracts the earth b) is the same as the force with which the moon attracts the earth c) is more than the force with which the moon attracts the earth d) varies with the phase of the moon

b) is the same as the force with which the moon attracts the earth

Which statement is true for an object dropped from rest? a) it falls about twice as far in the second second after being let go as in the first second b) it falls about three times as far in the second second after being let go as in the first second c) it falls the same distance in the second second after being let go as in the first second d) it falls about half the distance in the second second after being let go as in the first second

b) it falls about three times as far in the second second after being let go as in the first second

You are riding a bicycle at a constant speed when you throw a ball vertically upward. It will land a) in front of you b) on your head c) behind you d) any of the above, depending on the ball's speed

b) on your head

The radius of the circle in which an object is moving at constant speed is doubled. The requiered centripetal force is a) one quarter as great as before b) one half as great as before c) twice as great before d) 4 times as great as before

b) one half as great as before

According to the physicist Richard Feynman, "Science is the culture of doubt." What does this mean? a) science is a doubtful and unreliable guide to the natural world because it is always changing b) science is a reliable guide to the natural world precisely because it is self-correcting by being open to change in the light of new evidence c) science is always arriving at new hypotheses, so present theories like The Big Bang are to be treated with suspicion d) scientific theories are just educated guesses, and therefore subject to doubt

b) science is a reliable guide to the natural world precisely because it is self-correcting by being open to change in the light of new evidence

Which is correct regarding scientific models and their usefulness? a) scientific models are a simplified version of reality, and therefore represent the important aspects of nature in all of its complexity b) scientific models approximate reality in a form that isolates the most important features of a system, and therefore simplifies the problem c) scientific models must be exact representations of reality in order to be useful d) scientific models never change once established and therefore provide continuity

b) scientific models approximate reality in a form that isolates the most important features of a system, and therefore simplifies the problem

If the moon were half as far from the earth as it is today, how would the gravitational force it exerts on the earth compare with the force it exerts today? a) the force would double b) the force would be four times what it is today c) the force would be one-fourth what it is today d) the force would remain about the same e) the force would be cut in half

b) the force would be four times what it is today

The acceleration of a stone thrown upward is a) greater than that of a stone thrown downward b) the same as that of a stone thrown downward c) less than that of a stone thrown downward d) zero until it reaches the highest point in its path

b) the same as that of a stone thrown downward

An astronaut inside an orbiting satellite feels weightless because a) he or she is wearing a space suit b) the satellite is falling toward the earth just as fast as the astronaut is, so there is no upward force on him or her c) there is no gravitational pull from the earth so far away d) the suns gravitational pull balances out the earths gravitational pull

b) the satellite is falling toward the earth just as fast as the astronaut is, so there is no upward force on him or her

A year corresponds to the time it takes for an observer on the earth to see _________ a) the sun migrate westward completely around the sky b) the sun migrate eastward completely around the sky c) the sun overhead at the same angle d) the same constellations reappear in the night sky

b) the sun migrate eastward completely around the sky

An object moving in a circle at constant speed is accelerated a) in the direction of its motion. b) toward the center of the circle. c) away from the center of the circle. d) Any of these choices, depending on the circumstances.

b) toward the center of the circle.

A meter is not equal to a) 100 cm. b) 103 mm. c) 0.01 km. d) 10-3 km.

c) 0.01 km.

A ship travels 200 km to the south and then 400 km to the west. The ship's displacement from its starting point is a) 200 km b) 400 km c) 450 km d) 600 km

c) 450 km

A person is 180 cm tall. This is equivalent to a) 4 ft 6 in b) 5 ft 9 in c) 5 ft 11 in d) 7 ft 1 in

c) 5 ft 11 in

Is an astronaut orbiting in space actually weightless? a) Yes, the astronaut still has mass, but has no gravitational force, so no weight b) Yes, due to the lack of an atmosphere c) No, the astronaut has weight but, being in freefall, feels weightless d) Yes, due to the lack of gravity

c) No, the astronaut has weight but, being in freefall, feels weightless

In which of the following examples is the motion of the car not accelerated? a) A car turns a corner at the constant speed of 20 km/h b) A car climbs a steep hill with its speed dropping from 60 km/h at the bottom to 15 km/h at the top c) a car climbs a steep hill at the constant speed of 40 km/h d) a car climbs a steep hill and goes over the crest and down on the other side, all at the same speed of 40 km/h

c) a car climbs a steep hill at the constant speed of 40 km/h

In order to cause something to move in a circular path, it is necessary to provide a) a reaction force b) an inertial force c) a centripetal force d) a gravitational force

c) a centripetal force

If we know the magnitude and direction of the net force on an object of known mass, Newton's second law of motion lets us finds its a) position b) speed c) acceleration d) a net force always acts on it

c) acceleration

which of the following statements is incorrect? a) all vector quantities have directions b) all vector quantities have magnitudes c) all scalar quantities have directions d) all scalar quantities have magnitudes

c) all scalar quantities have directions

High tide occurs at a given place a) only when the moon faces the place b) only when the moon is on the opposite side of the earth from the place c) both when the moon faces the place and when the moon is on the opposite side of the earth from the place d) when the place is halfway between facing the moon and being on the opposite side of the earth from the moon

c) both when the moon faces the place and when the moon is on the opposite side of the earth from the place

Tides are caused by a) only by the sun b) only by the moon c) by both the sun and the moon d) sometimes by the sun and sometimes by the moon

c) by both the sun and the moon

The earth and the moon exert equal and opposite forces on each other. The force the earth exerts on the moon a) is the action force b) is the reaction force c) can be considered either as the action or as the reaction force d) cannot be considered as part of an action-reaction pair because the forces act in opposite directions

c) can be considered either as the action or as the reaction force

The sun exerts a gravitational force on the earth and the earth exerts a gravitational force on the sun. The force the earth exerts a) is the action force. b) is the reaction force. c) can be considered either as the action or as the reaction force. d) is not part of an action-reaction pair because the earth and sun are not in contact with each other.

c) can be considered either as the action or as the reaction force.

According to Kepler's third law, the time needed for a planet to complete an orbit around the sun a) is the same for all the planets b) depends on the planets size c) depends on the planets distance from the sun d) depends on how fast the planet spins on its axis

c) depends on the planets distance from the sun

A car rounds a curve on a level road. The centripetal force on the car is provided by a) inertia b) gravity c) friction between the tires and the road d) the force applied to the steering wheel

c) friction between the tires and the road

A stone is thrown upward from a roof at the same time as another, identical stone is dropped from there. The two stones a) reach the ground at the same time. b) have the same speed when they reach the ground. c) have the same acceleration when they reach the ground. d) None of the choices are correct.

c) have the same acceleration when they reach the ground.

A box suspended by a rope is pulled to one side by a horizontal force. The tension in the rope a) is less than before b) is unchanged c) is greater than before d) may be any of the above, depending on how strong the force

c) is greater than before

A bullet is fired upward. As it rises, a) its mass and weight remain the same. b) its mass and weight decrease. c) its mass remains the same while its weight decreases. d) its mass decreases while its weight remains the same.

c) its mass remains the same while its weight decreases.

which of the following quantities is not a vector quantity a) velocity b) acceleration c) mass d) force

c) mass

What is the difference between spring tides and neap tides? a) spring tides are high tides, whereas neap tides are low tides b) spring tides are minimum tidal differences, whereas neap tides are maximum tidal differences c) spring tides are maximum tidal differences, whereas neap tides are minimum tidal differences d) spring tides occur in the spring, whereas neap tides occur in the fall

c) spring tides are maximum tidal differences, whereas neap tides are minimum tidal differences

two objects have the same size and shape but one of them is twice as heavy as the other. They are dropped simultaneously from a tower. If air resistance is negligible, a) the heavy object strikes the ground before the light one b) they strike the ground at the same time, but the heavy object has the higher speed c) they strike the ground at the same time and have the same speed d) they strike the ground at the same time, but the heavy object has the lower acceleration because it has more mass

c) they strike the ground at the same time and have the same speed

The usual tidal pattern in most parts of the world consists of a) a high tide one day and a low tide on the next b) one high tide and one low tide daily c) two high tides and two low tides daily d) three high tides and three low tides daily

c) two high tides and two low tides daily

Of the following, the longest is a) 1000 feet b) 500 m c) 1 km d) 1 mi

d) 1 mi

The prefix micro stands for a) 1/10 b) 1/100 c) 1/1000 d) 1/1,000,000

d) 1/1,000,000

A snail travels 45 cm in 20 min. Its average speed is a) 2.25 cm/h. b) 15 cm/h. c) 90 cm/h. d) 135 cm/h.

d) 135 cm/h.

The sum of two vectors is a minimum when the angle between them is a) 0 b) 45 c) 90 d) 180

d) 180

Which one of the following represents a vector quantity? a) 750 miles/h b) 60 cycles/second c) 220 volts d) 55 km/h toward the north

d) 55 km/h toward the north

Relative to what she weighs on the earth, an astronaut visiting another planet a) weighs less. b) weighs the same. c) weighs more. d) Any of these choices, depending on the planet.

d) Any of these choices, depending on the planet.

The planet closest to the sun is a) earth b) Venus c) Mars d) Mercury

d) Mercury

A planet not visible to the naked eye is a) Mars b) Venus c) Mercury d) Neptune

d) Neptune

When an object is accelerated, a) its direction never changes b) its speed always increases c) it always falls toward the earth d) a net force always acts on it

d) a net force always acts on it