physics exam 2 tx state

What will the kinetic energy of a pile driver ram be if it starts from rest and undergoes a 10 kJ decrease in potential energy? 10 kJ 5 kJ -10 kJ 0 kJ

10 KJ

What is the magnitude of Earth's gravitational force on a 1-kg body at Earth's surface? 6.67 × 10 -11 N 6.67 × 10 -11 kg 1 kg 10 N

10 N

A projectile is launched vertically at 100 m/s. If air resistance can be ignored, at what speed will it return to its initial level? 200 m/s 0 m/s 100 m/s 10 m/s

100 m/s

A force of 50 N is applied to the end of a lever, which is moved a certain distance. If the other end of the lever moves one-third as far, how much force does it exert? 150 N 100 N 50 N 16.7 N

150 N

If you push a crate horizontally with 100 N across a 10-m factory floor and the friction between the crate and the floor is a steady 70 N, how much kinetic energy does the crate gain? 300 J 700 J 400 J 1,000 J

300 J

An asteroid exerts a 360-N gravitational force on a nearby spacecraft. If the spacecraft moves to a position three times as far from the center of the asteroid, the force will be 120 N. 1080 N. 40 N. 360 N. zero.

40 N

A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1 s? For 2 s? 5 m, 20 m 5 m, 10 m 10 m, 20 m 10 m, 40 m

5 m, 20 m

How far does a projectile drop in 1 second? What is the speed needed for a projectile to orbit Earth? 5 m, 8 km/s 20 m, 32 km/s 10 m, 16 km/s 1 m, 1.6 km/s

5 m, 8 km/s

How far below a straight-line path does a horizontally projected projectile fall in the first second of fall? Zero meters 5 meters Depends on the projected speed 10 meters

5 meters

When the useful energy output of a simple machine is 100 J, and the total energy input is 200 J, the efficiency is _______. 100 %. 200 % 75 %. 50 %.

50%

What is the magnitude of the gravitational force between two 1-kg bodies that are 1 m apart? 6.67 × 10^ -11 N 1 kg 10 N 6.67 × 10^ -11 kg

6.67 × 10^ -11 N

A projectile is launched at 30° above ground level. What other angle at the same speed will result in the same range? 15° 60° 45° any angle at 60° or greater

60°

Why doesn't the Leaning Tower of Pisa topple over? A vertical line through the center of gravity passes through the center of its support base. The center of gravity is suspended below its support base. A vertical line through the center of gravity passes inside its support base. The center of gravity is at the center of the building.

A vertical line through the center of gravity passes inside its support base.

Distinguish between linear momentum and angular momentum. Angular momentum depends on tangential velocity, whereas linear momentum depends on the rotational velocity. Angular momentum depends on the distribution of mass times the total mass, whereas linear momentum depends only on the distribution of mass. Angular momentum depends on the total mass, whereas linear momentum depends on the distribution of mass. Angular momentum depends on the distribution of mass, whereas linear momentum depends on the total mass.

Angular momentum depends on the distribution of mass, whereas linear momentum depends on the total mass.

What is the law of inertia for rotating systems in terms of angular momentum? Angular momentum does not change without an applied external torque. Angular momentum does not change without a change in rotational inertia. Angular momentum does not change without a change in rotational velocity. Angular momentum does not change without an applied internal torque.

Angular momentum does not change without an applied external torque.

Consider three axes of rotation for a pencil: along the lead, at right angles to the lead at the middle, and at right angles to the lead at one end. Rate the rotational inertias about each axis from smallest to largest. Axis along the lead, through one end, through the center Axis through the center, through one end, along the lead Axis through one end, along the lead, through the center Axis along the lead, through the center, through one end

Axis along the lead, through the center, through one end

Who gathered the data that showed planets traveling in elliptical paths around the Sun? Who discovered elliptical orbits? Who explained them? Brahe, Kepler, Newton Kepler, Galileo, Newton Brahe, Newton, Kepler Kepler, Brahe, Newton

Brahe, Kepler, Newton

What is required to change the angular momentum of a system? External force External torque Force Torque

External torque

When is your weight measured as mg? For a mass accelerating downward with an acceleration g For a non-accelerating mass near the surface of Earth For a mass accelerating upward with an acceleration g near the surface of Earth For a mass near the surface of Earth in free fall

For a non-accelerating mass near the surface of Earth

Why does the vertical component of velocity for a projectile change with time, whereas the horizontal component of velocity doesn't change? Air resistance can be ignored. The projectile has vertical inertia but not horizontal inertia. Gravity is a purely vertical force. The projectile has horizontal inertia but not vertical inertia.

Gravity is purely vertical force

Why does the force of gravity change the speed of a satellite in an elliptical orbit? Gravity speeds up the satellite as it moves away and slows it on its return. The force of gravity is always tangent to the satellite motion. Gravity slows the satellite as it moves away and speeds it up on its return. The force of gravity is always perpendicular to the satellite motion.

Gravity slows the satellite as it moves away and speeds it up on its return.

At what part of an elliptical orbit does an Earth satellite have the greatest speed? The lowest speed? Greatest nearest Earth; lowest furthest from Earth It travels at a constant 8 km/s. Greatest at the focus inside Earth; lowest at the other focus Lowest nearest Earth; greatest furthest from Earth

Greatest nearest Earth; lowest furthest from Earth

A stone is thrown upward at an angle. What happens to the magnitude of the vertical component of its velocity as it rises? As it falls? It increases while rising, but it decreases while falling. It decreases while rising and while falling. It decreases while rising, but it increases while falling. Rising or falling, it does not change.

It decreases while rising, but it increases while falling.

Why is centrifugal force in a rotating frame called a "fictitious force"? An outside observer has to add in the centrifugal force to understand motion in a rotating frame of reference. It is not a fundamental force of nature. Instead, it is a force that only appears in an accelerating frame of reference. Newton made it up. It is a force physicists had to insert to make the equations work out right.

It is not a fundamental force of nature. Instead, it is a force that only appears in an accelerating frame of reference.

What is meant by the "lever arm" of a torque? It is the perpendicular distance from the rotational axis to the line along which the force acts. It is the angle between the applied force vector and the rotational axis. It is the distance between the point at which a force is applied and the rotational axis. It is the distance between the point at which a force is applied and the center of mass of an object.

It is the perpendicular distance from the rotational axis to the line along which the force acts.

How does the thickness of paint sprayed on a surface change when the sprayer is held twice as far away? It is ¼ as thick. It is the same thickness. It is twice as thick. It is ½ as thick.

It is ¼ as thick.

Compared with a car moving at some original speed, how much work must the brakes of a car supply to stop a car that is moving twice as fast? How will the stopping distances compare? There is no change in the work and stopping distance. It takes four times the work and four times the stopping distance. It takes twice the work and twice the stopping distance. It takes half the work and half the stopping distance.

It takes four times the work and four times the stopping distance.

If you toss a stick into the air, it appears to wobble all over the place. Specifically, about what place does it wobble? It will rotate about one end. It will rotate about the place it was last touched by your hand. It will rotate about the center of mass.

It will rotate about the center of mass.

A car is raised a certain distance in a service-station lift, thus giving it potential energy relative to the floor. If it were raised twice as high, how much more potential energy would it have? It would have equal and opposite potential energy. It would have twice as much potential energy. It would have the exact same potential energy. It would have half as much potential energy.

It would have twice as much potential energy.

art A If the string that holds a whirling can in its circular path breaks, what kind of force causes it to move in a straight- line path: centripetal, centrifugal, or no force? What law of physics supports your answer? Centrifugal; Newton's third law Centrifugal; Newton's first law No force; Newton's first law Centripetal; Newton's second law.

No force; Newton's first law

Which energy production method does not ultimately depend on the Sun? Wind power Photovoltaic cells. Nuclear fission Fossil fuels

Nuclear fission

What is the ultimate source of geothermal energy? Gravity Kinetic energy of Earth in its orbit Nuclear power in Earth's interior The Sun

Nuclear power in Earth's interior

For an Earth satellite in circular orbit, list all the values that do not change. Only speed, gravitational force, and distance from Earth Speed and gravitational force only Speed only Speed, gravitational force, and distance from the Sun and Earth

Only speed, gravitational force, and distance from Earth

A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls? Rising or falling, it does not change. It increases while rising and while falling. It decreases while rising, but it increases while falling. It increases while rising, but it decreases while falling

Rising or falling, it does not change.

If you hang at rest by your hands from a long vertical rope, where is your center of gravity with respect to the rope? At the end of the rope Somewhere straight below where your hands grab the rope Somewhere straight above where your hands grab the rope Where your hands grab the rope

Somewhere straight below where your hands grab the rope

On a rotating turntable, how do tangential speed and rotational speed vary with distance from the center? Both are constant. Rotational speed increases with distance. Tangential speed is constant. Both increase in speed with distance. Tangential speed increases with distance. Rotational speed is constant.

Tangential speed increases with distance. Rotational speed is constant.

Describe how the gravitational forces from the Sun and the Moon compare from one side of Earth to the other. The Sun exerts a stronger force on the side of Earth furthest from the Sun, and the Moon exerts a stronger force on the side nearest the Moon. The Sun exerts a stronger force on the side of Earth furthest from the Sun, and the Moon exerts a stronger force on the side furthest from the Moon. The Sun exerts a stronger force on the side of Earth nearest the Sun, and the Moon exerts a stronger force on the side furthest from the Moon. The Sun exerts a stronger force on the side of Earth nearest the Sun, and the Moon exerts a stronger force on the side nearest the Moon.

The Sun exerts a stronger force on the side of Earth nearest the Sun, and the Moon exerts a stronger force on the side nearest the Moon.

Two cars are raised to the same elevation on service-station lifts. If one car is twice as massive as the other, compare their gains of potential energy. The car with twice the mass has twice the potential energy. The less massive car has equal and opposite potential energy compared to the more massive car. Both cars have the same potential energy. The car with twice the mass has half the potential energy.

The car with twice the mass has twice the potential energy.

Inertia depends on mass; rotational inertia depends on mass and something else. What? The tangential speed of the rim The distribution of mass along the axis of rotation The distribution of mass about the axis of rotation The angular speed

The distribution of mass about the axis of rotation

What happens to the force of attraction between two planets when the distance between them is doubled? The force decreases to one quarter. The force decreases to half. The force doubles. The force remains the same.

The force decreases to one quarter.

State Newton's law of universal gravitation in words. Then do the same with one equation. The force is proportional to the product of two masses and inversely proportional to the distance between their centers: F ~ m1m2/d. The force is proportional to the product of two masses and inversely proportional to the square of the distance between their centers: F ~ m1m2/d2. The force is proportional to the product of two masses: F ~ m1m2. The force is proportional to the product of two masses and to the square of the distance between their centers: F ~ m1m2d2.

The force is proportional to the product of two masses and inversely proportional to the square of the distance between their centers: F ~ m1m2/d2.

A tapered cup rolled on a flat surface makes a circular path. What does this tell you about the tangential speed of the rim of the wide end of the cup compared with that of the rim of the narrow end? The tangential speed of the wide end is zero. The tangential speed is the same for both ends. The tangential speed of the wide end is faster. The tangential speed of the wide end is slower.

The tangential speed of the wide end is faster.

What is the Newtonian synthesis? His naming of the spectrum, ROYGBIV His alchemical work on alloys The union of terrestrial laws and cosmic laws His invention of calculus

The union of terrestrial laws and cosmic laws

Do tides depend more on the strength of gravitational pull or on the difference in strengths? Explain. Tides depend only on the strength. Tides depend only on the difference. Tides depend weakly on the difference and strongly on the strength. Tides depend on both the strength and the difference equally.

Tides depend only on the difference.

How can a projectile "fall around the Earth"? A projectile can "fall around Earth" if the distance it falls matches the curvature of Earth. In a circular orbit around a spherical planet, the force and the fall are always toward the center. The projectile falls 5 m for every 8 km and so does Earth. All of the above.

all of the above

How can gravity be simulated in an orbiting space station? Spin a station shaped like a bicycle wheel Spin two pods connected by a cable Rotate a cylinder to create centrifugal force as viewed by a person on the inside of the curved outer wall All of the above

all of the above

You experience weightlessness in a freely falling elevator. momentarily when you step off a chair. in the absence of a supporting surface. all of the above

all of the above

Rate this statement: No force due to Earth's gravity acts on astronauts inside the orbiting space station. always false sometimes true while in orbit always true while in orbit

always false

The center of gravity of a basketball is located _______. at its geometrical center at a point opposite to its center of mass at the point of application when balanced in the material making up its mass

at its geometrical center

Earth's gravitational field extends both inside and outside Earth and throughout the entire universe. only above and beyond Earth's surface and cancels inside Earth. neither of these

both inside and outside Earth and throughout the entire universe.

When the rotational speed of a rotating system doubles, its angular momentum _______. remains unchanged doubles reduces to zero quadruples

doubles

Kepler was the first to be credited for discovering that planets follow __________. curved paths elliptical paths parabolas circular paths

elliptical paths

Exactly what is it that enables an object to do work? Impulse Momentum Heat Energy

energy

The torque exerted by a crowbar on an object increases with increased _______. energy of application force and leverage distance rotational inertia force

force and leverage distance

How far must one travel to escape Earth's gravitational field? to a region beyond the solar system to a region above Earth's atmosphere to a region well beyond the Moon forget it; you can't travel far enough.

forget it; you can't travel far enough.

When a rock tied to a string is whirled in a horizontal circle, doubling the speed _______. doubles the tension in the string doubles the velocity, but the string tension remains the same decreases the velocity quadruples the tension in the string

quadruples the tension in the string

For an Earth satellite in an elliptical orbit, list all the values that do change. Speed Speed, gravitational force, and distance from Earth Speed, gravitational force, and distance from the Sun and Earth Speed and gravitational force

speed, gravitational force, and distance from earth

How much time does it take for a complete revolution of a satellite in close orbit about Earth? 45 minutes 24 hours 90 minutes 27.3 days

90 minutes

What happens to the force of attraction between two planets when the masses of both are doubled? The force doubles. The force remains the same. The force increases by 16. The force quadruples.

The force quadruples.

Why is it important that the projectile in the preceding question be 100 km or higher above Earth? To avoid air resistance To reduce the curvature of the orbit To be far enough away that gravity is negligible To keep above the highest mountains

to avoid air resistance

Recycled energy is mainly _______. energy that has been destroyed thermal energy kinetic or potential energy. use of energy otherwise wasted

use of energy otherwise wasted

A force sets an object in motion. When the force is multiplied by the time of its application, we call the quantity impulse, and an impulse changes the momentum of that object. What do we call the quantity force multiplied by distance? Power Work Heat Impulse

work

A projectile is launched upward at an angle of 70° from the horizontal and strikes the ground a certain distance downrange. For what other angle of launch at the same speed would this projectile land just as far away? 10° 30° 20° 45°

20°

If a skater who is spinning pulls her arms in so as to reduce her rotational inertia by half, by how much will her angular momentum change? By how much will her rate of spin change? Her angular momentum is cut in half. Her spin rate does not change. Her angular momentum is doubled. Her spin rate is doubled. Her angular momentum does not change. Her spin rate doubles. Her angular momentum is cut in half. Her spin rate is cut in half.

Her angular momentum does not change. Her spin rate doubles.

Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was accelerating upward? Downward? More compressed while accelerating upward and while accelerating downward Less compressed while accelerating upward and while accelerating downward Less compressed while accelerating upward, but more compressed while accelerating downward More compressed while accelerating upward, but less compressed while accelerating downward

More compressed while accelerating upward, but less compressed while accelerating downward

Which has the higher tides: spring tides or neap tides? Why? Neap tides are higher, because the tides from the Moon and Sun add together. Spring tides are higher, because the tides from the Moon and Sun partially cancel. Spring tides are higher, because the tides from the Moon and Sun add together. Neap tides are higher, because the tides from the Moon and Sun partially cancel.

Spring tides are higher, because the tides from the Moon and Sun add together.

An apple hanging from a limb has potential energy because of its height. If it falls, what becomes of this energy just before it hits the ground? When it hits the ground? The energy is kinetic energy before it hits the ground; it is thermal energy after. The energy is potential energy before it hits the ground; it is thermal energy after. The energy is thermal energy before it hits the ground; it is kinetic energy after. The energy is kinetic energy before it hits the ground; it is potential energy after.

The energy is kinetic energy before it hits the ground; it is thermal energy after.

What did Kepler discover about the periods of planets and their distances from the Sun? The period cubed was proportional to the distance squared. The period squared was proportional to the distance cubed. The period was proportional to the radius. The period was inversely proportional to the radius.

The period squared was proportional to the distance cubed.

Which will have the greater acceleration rolling down an incline: a hoop or a solid disk? Why? The solid disk will because the mass is closer to the axis of rotation. Both will have the same acceleration because they have the same rotational inertia. The hoop will because the mass is furthest from the axis of rotation. The solid disk will because it is heavier.

The solid disk will because the mass is closer to the axis of rotation.

If you are not wearing a seat belt in a car that rounds a curve, and you slide across your seat and slam against a car door, what kind of force is responsible for your slide: centripetal, centrifugal, or no force? There is no force as viewed by someone outside the car. To them you move in a straight line. It is centrifugal force as viewed by someone outside the car. It is centripetal force, but only as viewed by someone inside the car. Centripetal force

There is no force as viewed by someone outside the car. To them you move in a straight line.

Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was moving upward at constant velocity? Downward at constant velocity? More compressed while moving upward and less compressed while moving downward Less compressed while moving upward and more compressed while moving downward There would be no more compression and no more expansion for both upward and downward motion. More compressed while moving upward and while moving downward

There would be no more compression and no more expansion for both upward and downward motion.

What does a torque tend to do to an object? Torque tends to decrease the rotational inertia of the object. Torque tends to increase the linear speed of the object. Torque tends to twist or change the state of rotation of the object. Torque tends to increase the rotational inertia of the object.

Torque tends to twist or change the state of rotation of the object.

When you whirl a can at the end of a string in a circular path, what is the direction of the force you exert on the can? Tangent to the circle in the direction of motion of the can Radially outward from the center of the circle Toward the center of the circle Tangent to the circle and opposite in direction to the motion of the can

Toward the center of the circle

When G was first measured by Henry Cavendish, newspapers of the time hailed his experiment as the "weighing Earth experiment." Why? By dropping a large lead sphere, you can measure the acceleration of Earth and find its mass. With a known mass and the radius of the Earth, you can calculate the unknown mass of Earth. With a known mass and a scale, you can calculate the unknown mass of Earth. With a known mass, a scale, and the radius of Earth, you can calculate the unknown mass of Earth if you know G.

With a known mass, a scale, and the radius of Earth, you can calculate the unknown mass of Earth if you know G.

Where do you weigh more: at the bottom of Death Valley or atop one of the peaks of the Sierra Nevada? Why? You weigh more in Death Valley because you are closer to the center of Earth. You weigh more in Death Valley because more atmosphere pushes down on you. You weigh more on the summit, because the higher you go, the harder you fall. You weigh more on the summit because the air buoys you up less.

You weigh more in Death Valley because you are closer to the center of Earth.

What is the magnitude of the gravitational field at Earth's center? g/2 N/kg 2g N/kg Zero N/kg g N/kg

Zero N/kg

If the Sun were twice as massive the pull of Earth on the Sun would double. its pull on Earth would double. both of these neither of these

both of these

Which requires more work: lifting a 50-kg sack a vertical distance of 2 m or lifting a 25-kg sack a vertical distance of 4 m? Both take the same 1000 J. The sack lifted 4 m requires more work. The 50 kg sack requires more work. The 25 kg sack requires more work.

both take the same 1000 J.

When traveling twice as fast your kinetic energy is increased _______. by two. by three. by four. not at all.

by four

Energy cannot be _______. transferred. transformed. transferred, transformed, or destroyed. destroyed.

destroyed

When a rock tied to a string whirled in a horizontal circle somehow doubles in mass but keeps the same speed, the string tension _______. remains the same decreases increases by four doubles

doubles

When you lift twice the load twice as high, in half the time, the increase in potential energy is _______. the same. twice as much. four times. three times.

four times

The work that is done when twice the load is lifted twice the distance is _______. the same. twice as much. four times as much. three times as much

four times as much

The tangential speed on the outer edge of a rotating carousel is _______. the same as toward the center greater than toward the center less than toward the center four times as great for twice the distance

greater than toward the center

Where is the center of mass of a hollow soccer ball? At the lowest point of the ball At the top-dead-center of the ball Halfway between the center and the lowest point of the ball In the center of the ball

in the center of the ball

The direction of a gravitational field is away from the center of gravity of an object. in the same direction as gravitational attraction. opposite to the direction of gravitational attraction

in the same direction as gravitational attraction.

If the mass of Earth somehow increased with no change in radius, your weight would stay the same. increase also. decrease.

increase also

Rotational inertia about the midpoint of an object becomes greater with _______. decreased mass increased mass decreased mass and decreased distance to mass concentration increased mass and increased distance to mass concentration

increased mass and increased distance to mass concentration

The horizontal and vertical components of velocity for a projectile are __________. equal for angles greater than 45° dependent on each other parts of a parabola independent of each other

independent of each other

As distance increases between most of the mass of an object and its center of rotation, how does rotational inertia change? It goes to zero. It stays the same. It increases. It decreases.

it increases

What is the unit of work? newton kg m/s joule watt

joule

What are the units of measurement for tangential speed? For rotational speed? m/s for both m/s for tangential, RPM for rotational RPM for both RPM for tangential, m/s for rotational

m/s for tangential, RPM for rotational

The constant G in Newton's equation _______. produces equilibrium was measured by Newton makes the units of measurement consistent shows gravity to be a relatively huge force

makes the units of measurement consistent

The amount of gravitational force that acts on a space vehicle while in Earth orbit is nearly zero. nearly as much as the vehicle's weight on Earth's surface. the same as the vehicle's weight on Earth's surface.

nearly as much as the vehicle's weight on Earth's surface.

The force of gravity acting on you will increase if you burrow deep inside Earth. stand on a planet with a shrinking radius. both of these neither of these

stand on a planet with a shrinking radius

Isaac Newton synthesized _______. the pulls of the planets on one another the pulls of the Moon and Earth terrestrial and cosmic laws the extent to which gravity extends in the universe

terrestrial and cosmic laws

Why doesn't the force of gravity change the speed of a satellite in circular orbit? Satellites orbit at a height where gravity is essentially zero. The inertia of the fast satellite is so great that gravity can be ignored. Air resistance counteracts the effects of gravity. The force is at a right angle to the velocity.

the force is at a right angle to the velocity

When one does twice the work in twice the time, the power expended is _______. four times as much twice as much. three times as much the same.

the same

Fossil fuels, hydroelectric power, and wind power ultimately get their energy from _______. Earth's nuclear energy. greenhouse gases potential energy the Sun

the sun

Why are occupants of the International Space Station weightless? They are in free fall. They are so far from Earth that gravity is essentially zero. Centripetal force cancels gravity in the space station. The floor of the space station is made from cavorite, which blocks gravity.

they are in free fall