Physics Exam 3
A 1.0-kg wheel in the form of a solid disk rolls along a horizontal surface with a speed of 6.0 m/s. What is the total kinetic energy of the wheel? a) 9.0 J b) 18 J c) 27 J d) 36 J e) 54 J
c) 27 J
3.7.2 gravity questions on live
a)
Consider the following pairs of objects with varying masses and separation distances. Which of these pairs has the smallest gravitational potential energy? a) 1 b) 2 c) 3 d) 4 e) 3 and 4 are equally small
c) 3
The wheels of a bicycle have a radius of r meters. The bicycle is traveling along a level road at a constant speed v m/s. Which one of the following expressions may be used to determine the angular speed, in rev/min, of the wheels? a) v / r b) pi *r / 30r c) 30v / pi*r d) 30v / 2pi *r e) 60v / pi *r
c) 30v /pi*r
When considering the gravitational force acting on a group of particles or an extended body, how does Newton's law of gravitation apply? a) An extended body is broken down into infinitesimal particles that are mathematical points and massless. Under these conditions, Newton's law of gravitation is applied to each particle; and the net force is the sum of the individual forces. b) If an extended body can be broken down into spherical particles then, Newton's law of gravitation is applied to each particle; and the net force is the scalar sum of the individual forces. c) An extended body is broken down into infinitesimal particles. Under these conditions, Newton's law of gravitation is applied to each particle; and the net force is the vector sum of the individual forces
c) An extended body is broken down into infinitesimal particles. Under these conditions, Newton's law of gravitation is applied to each particle; and the net force is the vector sum of the individual forces
A planet is following a slightly elliptical orbit as it orbits the Sun. Which of the following explanations best explains why the planet moves faster in its orbit when it is closest to the Sun? a) Because no external forces are acting on the system, the total linear momentum of the system must be conserved. b) The gravitational attraction between the planet and the Sun results in a torque on the planet and the total angular momentum of the system is not conserved. c) Because no external forces are acting on the system, the total angular momentum of the system must be conserved. d) Because the system is isolated, the total kinetic energy of the planet must be conserved. e) Because the mass of the planet is not uniformly distributed, the gravitational force on the planet will vary the most when it is far from the Sun and least when it is close to the Sun
c) Because no external forces are acting on the system, the total angular momentum of the system must be conserved.
Consider the object shown. A bottle is inserted into a board that has a hole in it. The bottle and board are then set up on the table and are in equilibrium. Which of the points indicated is the most likely location for the center of mass for the bottle and board system? a) A b) B c) C d) D e) E
c) C
10.9.3. Consider the three situations shown in the figure. Three forces act on the triangular object in different ways. Two of the forces have magnitude F and one of the forces has a magnitude 2F. In which case(s), if any, will the object be in equilibrium? In each case, the forces may act at the center of gravity or at the center of a corner. a) A only b) B only c) C only d) A and C e) A and B e) A and B
c) C only
Joe has volunteered to help out in his physics class by sitting on a stool that easily rotates. Joe holds the dumbbells out as shown as the stool rotates. Then, Joe drops both dumbbells. Then, the angular momentum of Joe and the stool change, but the angular velocity does not change. Which of the following choice offers the best explanation? a) The force exerted by the dumbbells acts in opposite direction to the torque. b) Angular momentum is conserved, when no external forces are acting. c) Even though the angular momentum decreases, the moment of inertia also decreases. d) The decrease in the angular momentum is balanced by an increase in the moment of inertia. e) The angular velocity must increase when the dumbbells are dropped.
c) Even though the angular momentum decreases, the moment of inertia also decreases.
A circular hoop rolls without slipping on a flat horizontal surface. Which one of the following is necessarily true? a) All points on the rim of the hoop have the same speed. b) All points on the rim of the hoop have the same velocity. c) Every point on the rim of the wheel has a different velocity. d) All points on the rim of the hoop have acceleration vectors that are tangent to the hoop. e) All points on the rim of the hoop have acceleration vectors that point toward the center of the hoop
c) Every point on the rim of the wheel has a different velocity.
How does the Earth's gravitational force on you change, if at all, as you drill deeper into the Earth's crust and descend? a) It remains constant. b) It decreases with increasing depth. c) It increases with increasing depth
c) It increases with increasing depth
In the seventeenth century, French mathematician Gilles de Roberval developed a balance, shown in part A in the figure, for commercial weighing and it is still in use today. A variation of this device, shown part B of the figure, is used for physics demonstrations. In this case, the two triangular objects have equal mass and rest on the two horizontal arms at an equal distance from the vertical bars. When the system is released, there is no movement because the system is in equilibrium. One of the objects is then slid to the right as shown in part C, what will happen when the system is released? a) The arm on the right will go up. b) The arm on the left will go up. c) Neither arm will move c) Neither arm will move.
c) Neither arm will move.
Joe has volunteered to help out in his physics class by sitting on a stool that easily rotates. Joe holds the dumbbells out as shown as the stool rotates. Then, Joe drops both dumbbells. How does the angular momentum of Joe and the stool change, if at all? a) The angular momentum increases. b) The angular momentum decreases, but it remains greater than zero kg*m^2/s. c) The angular momentum remains the same. d) The angular momentum quickly decreases to zero kg*m^2/s.
c) The angular momentum remains the same.
The Earth, which has an equatorial radius of 6380 km, makes one revolution on its axis every 23.93 hours. What is the tangential speed of Nairobi, Kenya, a city near the equator? a) 37.0 m/s b) 74.0 m/s c) 148 m/s d) 232 m/s e) 465 m/s
e) 465 m/s
What is the direction of the Earth's orbital angular momentum as it spins about its axis? a) north b) south c) east d) west e) radially inward
a) north
SEE 11.11.7 in slides
c)
A bicycle wheel of radius 0.70 m is turning at an angular speed of 6.3 rad/s as it rolls on a horizontal surface without slipping. What is the linear speed of the wheel? a) 1.4 m/s b) 28 m/s c) 0.11 m/s d) 4.4 m/s e) 9.1 m/s
d) 4.4 m/s
An astronaut, whose mass on the surface of the Earth is m, orbits the Earth in the space shuttle at an altitude of 450 km. What is her mass while orbiting in the space shuttle? a) 0.125m b) 0.25m c) 0.50m d) 0.75m e) m
e) m
The following diagram shows two smaller planets of mass m and one larger planet of mass 4m, aligned and separated by distance d between each planet. Use the diagram to answer the next 2 questions. 15. Planet A experiences a gravitational force by Planet C that is ______ that by Planet B. a. less than b. equal to c. greater than d. cannot be determined with the given information. 16. Which one of the following gravitational forces is strongest? a. The force by Planet A on Planet B. b. The force by Planet A on Planet C. c. The force by Planet B on Planet C. d. The force by Planet C on Planet A.
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An object with a triangular cross-section is free to rotate about the axis shown. Four forces with identical magnitudes are exerted on the object as shown. Which one of the forces, if any, exerts the largest torque on the object? a) 1 b) 2 c) 3 d) 4 e) The same torque is exerted by each force.
c) 3
In a distant solar system where several planets are orbiting a single star of mass M, a large asteroid collides with a planet of mass m orbiting the star at a distance r. As a result of the collision, the planet is knocked out of its orbit, such that it leaves the solar system. Which of the following expressions gives the minimum amount of energy that the planet must receive in the collision to be removed from the solar system? a) (G)(Mm / r) b) (G)(Mm / r^2) c) (G)(Mm / sqrt(r)) d) Gm / r e) (G)(m/r^2)
a) (G)(Mm / r)
Josh is painting yellow stripes on a road using a paint roller. To roll the paint roller along the road, Josh applies a force of 15 N at an angle of 45 degrees with respect to the road. The mass of the roller is 2.5 kg; and its radius is 4.0 cm. Ignoring the mass of the handle of the roller, what is the magnitude of the tangential acceleration of the roller? a) 4.2 m/s^2 b) 6.0 m/s^2 c) 15 m/s^2 d) 110 m/s^2 e) 150 m/s^2
a) 4.2 m/s^2
Josh is painting yellow stripes on a road using a paint roller. To roll the paint roller along the road, Josh applies a force of 15 N at an angle of 45 degrees with respect to the road. The mass of the roller is 2.5 kg; and its radius is 4.0 cm. Ignoring the mass of the handle of the roller, what is the magnitude of the tangential acceleration of the roller? a) 4.2 m/s^2 b) 6.0 m/s^2 c) 15 m/s^2 d) 110 m/s^2 e) 150 m/s^2
a) 4.2 m/s^2
The corner of a rectangular piece of wood is attached to a rod that is free to rotate as shown. The length of the longer side of the rectangle is 4.0 m, which is twice the length of the shorter side. Two equal forces are applied to two of the corners with magnitudes of 22 N. What is the magnitude of the net torque and direction of rotation on the block, if any? a) 44 N*m, clockwise b) 44 N*m, counterclockwise c) 88 N*m, clockwise d) 88 N*m, counterclockwise e) zero N*m, no rotation
a) 44 N*m, clockwise
The planet Mercury takes only 88 Earth days to orbit the Sun. The orbit is nearly circular, so for this exercise, assume that it is. What is the angular velocity, in radians per second, of Mercury in its orbit around the Sun? a) 8.3 × 10^-7 rad/s b) 2.0 × 10^-5 rad/s c) 7.3 × 10^-4 rad/s d) 7.1 × 10^-2 rad/s e) This cannot be determined without knowing the radius of the orbit
a) 8.3 × 10^-7 rad/s
A ball is spinning about an axis that passes through its center with a constant angular acceleration of pi rad/s^2. During a time interval from t1 to t2, the angular displacement of the ball is radians. At time t2, the angular velocity of the ball is 2pi rad/s. What is the ball's angular velocity at time t1? a) 6.28 rad/s b) 3.14 rad/s c) 2.22 rad/s d) 1.00 rad/s e) zero rad/s
c) 2.22 rad/s
Two satellites of masses m and 2m are at opposite sides of the same circular orbit about the Earth. Which one of the following statements is true? a) The magnitude of the gravitational force is greater for the satellite of mass 2m than it is for the other satellite. b) The magnitude of the gravitational force is the same for both satellites; and it is greater than zero newtons. c) Since the satellites are moving at a constant velocity, the gravitational force on the satellites must be zero newtons. d) The magnitude of the gravitational force is greater for the satellite of mass m than it is for the other satellite. e) The satellite of mass 2m must move faster in the orbit than the other and eventually they will be on the same side of the Earth.
a) The magnitude of the gravitational force is greater for the satellite of mass 2m than it is for the other satellite.
An interesting method for exercising a dog is to have it walk on the rough surface a circular platform that freely rotates about its center as shown. When the dog begins walking near the outer edge of the platform as shown, how will the platform move, if at all? Assume the bearing on which the platform can rotate is frictionless. a) When the dog walks, the platform will rotate counterclockwise when viewed from above. b) When the dog walks, the platform will rotate clockwise when viewed from above. c) When the dog walks, the platform will not rotate.
a) When the dog walks, the platform will rotate counterclockwise when viewed from above.
Six identical bricks are stacked on top of one another. Note that the vertical dashed line indicates that the left edge of the top brick is located to the right of the right side of the bottom brick. Is the equilibrium configuration shown possible,why or why not? a) Yes, this is possible as long as the combined center of gravity of the blocks above a given brick does not extend beyond the right side of the brick below. b) Yes, this is possible as long as the left side of each block is directly above the center of gravity of the brick directly below it. c) Yes, this is possible as long as the center of gravity of the blocks above a given brick remains directly above the center of gravity of the blocks below that brick. d) No, this is not possible because the center of gravity of the top two blocks extends beyond the right edge of the bottom two blocks. e) No, because the center of gravity of the top block is to the right of the third block from the top.
a) Yes, this is possible as long as the combined center of gravity of the blocks above a given brick does not extend beyond the right side of the brick below.
A solid sphere of radius R rotates about an axis that is tangent to the sphere with an angular speed w. Under the action of internal forces, the radius of the sphere increases to 2R. What is the final angular speed of the sphere? a) w / 4 b) w / 2 c) w d) 2w e) 4w
a) w/4
Two solid cylinders are rotating about an axis that passes through the center of both ends of each cylinder. Cylinder A has three times the mass and twice the radius of cylinder B, but they have the same rotational kinetic energy. What is the ratio of the angular velocities, wA/wB, for these two cylinders? a) 0.25 b) 0.50 c) 1.0 d) 2.0 e) 4.0
b) 0.50
Two solid disks, which are free to rotate independently about the same axis that passes through their centers and perpendicular to their faces, are initially at rest. The two disks have the same mass, but one of has a radius R and the other has a radius 2R. A force of magnitude F is applied to the edge of the larger radius disk and it begins rotating. What force must be applied to the edge of the smaller disk so that the angular acceleration is the same as that for the larger disk? Express your answer in terms of the force F applied to the larger disk. a) 0.25F b) 0.50F c) F d) 1.5F e) 2 F
b) 0.50F
Your weight here in the classroom is W. What would your weight be if you were orbiting the Earth in the Space Shuttle at an altitude of 400 km? a) 0.46W b) 0.89W c) W d) 0.97W e) zero
b) 0.89W
While excavating the tomb of Tutankhamun (d. 1325 BC), archeologists found a sling made of linen. The sling could hold a stone in a pouch, which could then be whirled in a horizontal circle. The stone could then be thrown for hunting or used in battle. Imagine the sling held a 0.050-kg stone; and it was whirled at a radius of 1.2 m with an angular speed of 2.0 rev/s. What was the angular momentum of the stone under these circumstances? a) 0.14 kg * m^2/s b) 0.90 kg * m^2/s c) 1.2 kg * m^2/s d) 2.4 kg * m^2/s e) 3.6 kg * m^2/s
b) 0.90 kg * m^2/s
The original Ferris wheel had a radius of 38 m and completed a full revolution (2pi radians) every two minutes when operating at its maximum speed. If the wheel were uniformly slowed from its maximum speed to a stop in 35 seconds, what would be the magnitude of the instantaneous tangential speed at the outer rim of the wheel 15 seconds after it begins its deceleration? a) 0.295 m/s b) 1.12 m/s c) 1.50 m/s d) 1.77 m/s e) 2.03 m/s
b) 1.12 m/s
Consider the drawing. A rope is wrapped around one-third of the circumference of a solid disk of radius R = 2.2 m that is free to rotate about an axis that passes through its center. The force applied to the rope has a magnitude of 35 N; and the disk has a mass M of 7.5 kg. Assuming the force is applied horizontally as shown and the disk is initially at rest, determine the amount of rotational work done until the time when the end of the rope reaches the top of the disk? a) 140 N b) 160 N c) 180 N d) 210 N e) 250 N
b) 160 N
In the distant future, a space ship will leave the Earth and travel to a planet where the acceleration due to gravity is one-third that on Earth, By what factor is the required velocity altered to leave the distant planet than it was to leave Earth? a) 1/3 b) 3^-1/2 c) 1 d) 3^1/2 e) 3
b) 3^-1/2
A bowling ball is rolling without slipping at constant speed toward the pins on a lane. What percentage of the ball's total kinetic energy is translational kinetic energy? a) 50 % b) 71 % c) 46 % d) 29 % e) 33 %
b) 71 %
A 1.0-m long steel bar is suspended from a rope from the ceiling as shown. The rope is attached to the bar at its mid-point. A force F1 directed at an angle theta is applied at one end. At the other end, a force is applied perpendicular to the bar. If the magnitudes of the two forces are equal, for which one of the following values of the angle theta will the net torque on the bar have the smallest magnitude? a) 0 degrees b) 90 degrees c) 135 degrees d) 180 degrees e) 27 degrees
b) 90 degrees
Joe has volunteered to help out in his physics class by sitting on a stool that easily rotates. As Joe holds the dumbbells out as shown, the professor temporarily applies a sufficient torque that causes him to rotate slowly. Then, Joe brings the dumbbells close to his body and he rotates faster. Why does his speed increase? a) By bringing the dumbbells inward, Joe exerts a torque on the stool. b) By bringing the dumbbells inward, Joe decreases the moment of inertia. c) By bringing the dumbbells inward, Joe increases the angular momentum. d) By bringing the dumbbells inward, Joe increases the moment of inertia. e) By bringing the dumbbells inward, Joe decreases the angular momentum.
b) By bringing the dumbbells inward, Joe decreases the moment of inertia.
A star is rotating about an axis that passes through its center. When the star "dies," the balance between the inward pressure due to the force of gravity and the outward pressure from nuclear processes is no longer present and the star collapses inward and its radius decreases with time. Which one of the following choices best describes what happens as the star collapses? a) The angular velocity of the star remains constant. b) The angular momentum of the star remains constant. c) The angular velocity of the star decreases. d) The angular momentum of the star decreases. e) Both angular momentum and angular velocity increase.
b) The angular momentum of the star remains constant.
Which one of the following statements concerning a planet orbiting the Sun is true? a) The gravitational force between the planet and Sun must be larger than the centripetal force needed to keep the planet in its orbit. b) The centripetal force that keeps the planet moving in a stable orbit is provided by the gravitational attraction between the planet and Sun. c) If the gravitational force between the planet and Sun is less than the centripetal force needed to keep the planet in its orbit the planet would spiral in until the planet reaches a stable orbit. d) The gravitational force of the planet that acts on the Sun is always smaller than the gravitational force of the Sun that acts on the planet. e) None of the above statements are true
b) The centripetal force that keeps the planet moving in a stable orbit is provided by the gravitational attraction between the planet and Sun.
At the circus, a clown balances a step ladder on his forehead. A few people in the audience notice that he is continually moving to keep the ladder from falling off his forehead. Why is this movement necessary? a) The clown is trying to apply a torque to the ladder in the direction opposite to other torques on the ladder. b) The clown is trying to keep the center of mass of the ladder directly above his head so that the torque due to the gravitational force is zero N*m. c) By rocking the ladder on his forehead, the ladder will be more stable than if it were stationary. This is similar to riding a bicycle. You can easily balance a bicycle when it's rolling, but not when it's stationary. d) This movement is not necessary. The clown is trying to make this look harder than it really is for entertainment value. The ladder will easily balance in the clown's forehead.
b) The clown is trying to keep the center of mass of the ladder directly above his head so that the torque due to the gravitational force is zero Nm.
Two objects that may be considered point masses are initially separated by a distance d. The separation distance is then decreased to d/3. How does the gravitational force between these two objects change as a result of the decrease? a) The force will not change since it is only dependent on the masses of the objects. b) The force will be nine times larger than the initial value. c) The force will be three times larger than the initial value. d) The force will be one third of the initial value. e) The force will be one ninth of the initial value.
b) The force will be nine times larger than the initial value.
The drawing shows a yo-yo in contact with a tabletop. A string is wrapped around the central axle. How will the yo-yo behave if you pull on the string with the force shown? a) The yo-yo will roll to the left. b) The yo-yo will roll to the right. c) The yo-yo will spin in place, but not roll. d) The yo-yo will not roll, but it will move to the left. e) The yo-yo will not roll, but it will move to the right.
b) The yo-yo will roll to the right.
The precession of a gyroscope is an example of which of the following principles? a) conservation of rotational energy b) conservation of angular momentum c) conservation of linear momentum d) conservation of total mechanical energy e) conservation of torque
b) conservation of angular momentum
A hollow cylinder of mass M and radius R rolls down an inclined plane. A block of mass M slides down an identical inclined plane. Complete the following statement: If both objects are released at the same time, a) the cylinder will reach the bottom first. b) the block will reach the bottom first. c) the block will reach the bottom with the greater kinetic energy. d) the cylinder will reach the bottom with the greater kinetic energy. e) both the block and the cylinder will reach the bottom at the same time.
b) the block will reach the bottom first.
Complete the following statement: For a wheel that turns with constant angular speed, a) each point on its rim moves with constant acceleration. b) the wheel turns through "equal angles in equal times." c) each point on the rim moves at a constant velocity. d) the angular displacement of a point on the rim is constant. e) all points on the wheel are moving at a constant velocity.
b) the wheel turns through "equal angles in equal times.
Consider the following three objects, each of the same mass and radius: (1) a solid sphere (2)a solid disk (3)a hoop All three are released from rest at the top of an inclined plane. The three objects proceed down the incline undergoing rolling motion without slipping. In which order do the objects reach the bottom of the incline? a) 3, 1, 2 b) 2, 3, 1 c) 1, 2, 3 d) 3, 2, 1 e) All three reach the bottom at the same time
c) 1, 2, 3
A 4.0-m board is resting directly on top of a 4.0-m long table. The weight of the board is 340 N. An object with a weight of 170 N is placed at the right end of the board. What is the maximum horizontal distance that the board can be moved toward the right such that the board remains in equilibrium? a) 0.75 m b) 1.0 m c) 1.3 m d) 1.5 m e) 2.0 m
c) 1.3 m
Joe has volunteered to help out in his physics class by sitting on a stool that easily rotates. Joe holds the dumbbells out as shown as the stool rotates. Then, Joe drops both dumbbells. How does the rotational speed of stool change, if at all? a) The rotational speed increases. b) The rotational speed decreases, but Joe continues to rotate. c) The rotational speed remains the same. d) The rotational speed quickly decreases to zero rad/s.
c) The rotational speed remains the same.
When using pruning shears, such as the pair shown, to cut a branch from a tree, it is better to insert the branch closer to the hinge than near the end of the shears. Which one of the following statements best explains the reason this observation is true? a) The torque acting on the branch is smallest near the hinge. b) The torque acting on the branch is largest near the hinge. c) The torque exerted on the shears yields the greatest force on the branch near the hinge. d) The long handles determine the force exerted on the branch, which is the same no matter where on the shears the branch is placed. e) The same torque is exerted on the shears and the branch, regardless of the force applied to the handles.
c) The torque exerted on the shears yields the greatest force on the branch near the hinge.
A hollow cylinder is rotating about an axis that passes through the center of both ends. The radius of the cylinder is r. At what angular speed w must the this cylinder rotate to have the same total kinetic energy that it would have if it were moving horizontally with a speed v without rotation? a) w = v^2 / 2r b) w = (v / r) sqrt(2) c) w = v/r d) w = v / 2r e) w = v^2 / r^2
c) w = v / r
If an object at the surface of the Earth has a weight W, what would be the weight of the object if it was transported to the surface of a planet that is one-sixth the mass of Earth and has a radius one third that of Earth? a) 3W b) 4W/3 c) W d) 3W/2 e) W/3
d) 3W/2
10.9.9 A long board is free to rotate about the pivot shown in each of the four configurations shown. Weights are hung from the board as indicated. In which of the configurations, if any, is the net torque about the pivot axis the largest? a) 1 b) 2 c) 3 d) 4 e) The net torque is the same for all four situations.
d) 4
Over the course of a day (twenty-four hours), what is the angular displacement of the second hand of a wrist watch in radians? a) 1440 rad b) 2880 rad c) 4520 rad d) 9050 rad e) 543 000 rad
d) 9050 rad
Consider the diamond-shaped object shown that is designed to balance on a thin thread like a tight rope walker at a circus. At the bottom of the diamond, there is a narrow notch that is as wide as the thickness of the thread. The mass of each of the metal spheres at the ends of the wires connected to the diamond is equal to the mass of the diamond. Which one of the points indicated is the most likely location of the center of gravity for this object? a) A b) B c) C d) D e) E
d) D
You are using a wrench in an attempt to loosen a nut by applying a force as shown. But this fails to loosen the nut. Which of the following choices is most likely to loosen this tough nut? a) Tie a rope of length 2L to the wrench at the same location and apply the same force as shown. b) Place a pipe of length 2L over the handle of the wrench and apply the same force to the opposite end (farthest from the nut). c) Double the force to 2. d) Doubling the length or doubling the force will have the same result, but doubling the length is easier. e) Continue applying the same force as in the drawing and eventually the nut will loosen.
d) Doubling the length or doubling the force will have the same result, but doubling the length is easier.
A spacecraft is in low orbit of the Earth with a period of approximately 90 minutes. By which of the following methods could the spacecraft stay in the same orbit and reduce the period of the orbit? a) Before launch, increase the mass of the spacecraft to increase the centripetal force on it. b) Remove any unnecessary equipment, cargo, and supplies to reduce the mass and decrease its angular momentum. c) Fire rockets to increase the tangential velocity of the ship. d) None of the above methods will achieve the desired effect
d) None of the above methods will achieve the desired effect
A particle is moving in a straight line at a constant velocity with respect to a point P. Which one of the following statements is true, if the angular momentum of the particle is zero kg * m/s^2? a) The particle cannot be traveling at constant velocity. b) The particle has passed through the point P. c) The particle cannot pass through the point P. d) The path of the particle must pass through point P
d) The path of the particle must pass through point P.
The position vector of a particle is directed along the positive y axis. What is the direction of the net torque acting on the particle if the net force is directed along the negative x direction? a) negative x direction b) positive x direction c) negative y direction d) positive z direction e) negative z direction
d) positive z direction
Four objects start from rest and roll without slipping down a ramp. The objects are a solid sphere, a hollow cylinder, a solid cylinder, and a hollow sphere. Each of the objects has the same radius and the same mass, but they are made from different materials. Which object will have the greatest angular speed at the bottom of the ramp? a) Since they are all starting from rest, all of the objects will have the same speed at the bottom as a result of the conservation of mechanical energy. b) solid sphere c) hollow cylinder d) solid cylinder e) hollow sphere
d) solid cylinder
The mean distance between the Earth and the Sun is 1.5 × 10^11 m. Using this fact and your knowledge of the period of the Earth's orbit around the Sun, determine the approximate mass of the Sun. a) 2 × 10^14 kg b) 2 × 10^18 kg c) 2 × 10^24 kg d) 2 × 10^27 kg e) 2 × 10^30 kg
e) 2 × 10^30 kg
The propeller of an airplane is at rest when the pilot starts the engine; and its angular acceleration is a constant value. Two seconds later, the propeller is rotating at 10 rad/s. Through how many revolutions has the propeller rotated through during the first two seconds? a) 300 b) 50 c) 20 d) 10 e) 5
e) 5
Jack is moving to a new apartment. He is loading a hand truck with four boxes: box A is full of books and weighs 133 N, box B has more books and weighs 111 N, box C contains his music collection on CDs and weighs 65 N, and box D contains clothes and weighs 47 N. The height of each box is 0.30 m. The center of gravity of each of the boxes is located at its center. In preparing to pull the hand truck up the ramp of the moving truck he rotates it to the position shown. What is the magnitude of the force that Jack is applying to the hand truck at a distance of 1.4 m from the axel of the wheel? a) 360 N b) 200 N c) 150 N d) 96 N e) 69 N
e) 69 N
Two ice skaters are holding hands and spinning around their combined center of mass, represented by the small black dot in Frame 1, with an angular momentum L. When the skaters are at the position shown in Frame 2, they release hands and move in opposite directions as shown in Frame 3. What is the angular momentum of the skaters in Frame 3? a) zero kg * m^2/s b) a value that is greater than zero kg * m^2/s, but less than L c) a value less than L and decreasing as they move further apart d) a value that is greater than L e) L
e) L
A cannon fires a ball vertically upward from the Earth's surface. Which one of the following statements concerning the net force acting on the ball at the top of its trajectory is correct? a) The net force on the ball is instantaneously equal to zero newtons at the top of the flight path. b) The direction of the net force on the ball changes from upward to downward. c) The net force on the ball is less than the weight, but greater than zero newtons. d) The net force on the ball is greater than the weight of the ball. e) The net force on the ball is equal to the weight of the ball
e) The net force on the ball is equal to the weight of the ball
Which one of the following statements concerning a wheel undergoing rolling motion is true? a) The angular acceleration of the wheel must be zero m/s^2. b) The tangential velocity is the same for all points on the wheel. c) The linear velocity for all points on the rim of the wheel is non-zero. d) The tangential velocity is the same for all points on the rim of the wheel. e) There is no slipping at the point where the wheel touches the surface on which it is rolling.
e) There is no slipping at the point where the wheel touches the surface on which it is rolling.
The second hand on a clock completes one revolution each minute. What is the direction of the angular momentum of the second hand as it passes the "12" at the top of the clock? a) toward the "12" b) toward the "3" c) toward the "6" d) outward from the face of the clock e) into the face of the clock
e) into the face of the clock
The position vector of a particle is directed along the positive y axis. What is the direction of the net force acting on the particle if the net torque is directed along the negative x direction? a) negative x direction b) positive x direction c) negative y direction d) positive z direction e) negative z direction
e) negative z direction
A 1.5-kg ball is tied to the end of a string. The ball is then swung at a constant angular velocity of 4pi rad/s in a horizontal circle of radius 2.0 m. What is the torque on the stone? a) 18 N*m b) 29 N*m c) 36 N*m d) 59 N*m e) zero N*m
e) zero N*m
