Physics Exam Three Review
A 13000 N vehicle is to be lifted by a 25 cm diameter hydraulic piston. What force needs to be applied to a 5.0 cm diameter piston to accomplish this? A) 520 N B) 13000 N C) 260 N D) 5200 N E) 2600 N
a
a pulsar (a rotating neutron star) emits pulses at a frequency of 0.40 kHz. The period of its rotation is a. 0.025 s b. 2.5 ms c. 2.5 s d. 0.25 s e. 25 ms
b
The speed of Halley's Comet, while traveling in its elliptical orbit around the Sun, a. increases as it nears the sun b. is constant c. decreases as it nears the sun d. is zero at four points in the orbit e. is zero at two points in the orbit
c
five forces act on a massless rod free to pivot at point P, as shown. Which force is producing a counter-clockwise torque about point P? a, b, c d, or e?
c
James moves in a circular paath (radius 15.0 m) with a speed of 60.0 m/s. His ANGULAR VELOCITY is a. 120 rad/s b. 120. rev/sec c. 120/pi rad/sec d. 120/pi rpm e. 120pi rad/s
d
an ice skater performs a pirouette by pulling in his outstretched arms close to his body. What happens to his moment of inertia about the axis of rotation? a. it changes, but it is impossible to tell which way b. it does not change c. it increases d. it decreases
d
The pressure differential across a wing cross section due to the difference in air flow is explained by a. Archimedes Principle b. Kepler's law c. Newton's third las d. Poiseuille's law e. Bernoulli's equatoin
e
Two horizontal curves on a bobsled run are banked at the same angle, but one has twice the radius of the other. The safe speed ( no friction needed to stay on the run) for the smaller radius curve is V. Therefore, the safe speed on the larger radius curve is a. 0.10 V b. 0.71 V c. 2. V d. 0.5 V e. 1.4 V
e
What is the centripetal acceleration of a point on the perimeter of a bicycle wheel of diameter 70. cm. when the bike is moving 8.0 m/s? a. 66 m/s2 b. 91 m/s2 c. 2.7*10^2 d/ 2.1*10^-2 e. 1.8*10^2 m/s2
e
a boy and a girl are riding on a merry go round that is turning. The boy is twice as far as the girl from the merry go round's center. If the bosy and girl are of equal masses, which statement is true about the boy's moment of inertia with respect to the axis of rotation? a. his moment of inertia is half the girl's b. his moment of inertia is twice the girl's c. the boy has a greater moment of inertia, but it is impossible to say exactly how much more d. the moment of inertia is the same for both e. his moment of inertia is 4 times the girl's
e
an object completely submerged in water must either rise or fall
false
Two children are riding on a merry go round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger centripetal acceleration? Child A or Child B
A
Two children are riding on a merry go round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger angular speed?
Child A
Two children are riding on a merry go round. Child A is at a greater distance from the axis of rotation than child B. Which child has the largest linear displacement? Child A, Child B, they have the same zero linear displacement, they have the same non-zero linear displacement, there is not enough information given to answer this question.
Child A
When a rigid body rotates about a fixed axis all the points in the body have the same centripetal acceleration.
False
When a rigid body rotates about a fixed axis all the points in the body have the same linear displacement.
False
When a rigid body rotates about a fixed axis all the points in the body have the same tangential speed.
False
when a rigid body rotates about a fixed axis all the points in the body have the same linear displacement
False
If an external pressure is applied ot a confined fluid, the pressure at every point within the fluid increases by that amount
True
Unbalanced torques produce rotational accelerations, and balanced torques produce rotational equilibrium
True
When a rigid body rotates about a fixed axis all the points in the body have the same angular displacement.
True
When a rigid body rotates about a fixed axis all the points int he body have the same angular speed.
True
when a rigid body rotates about a fixed axis all the points in the body have the same angular speed
True
A solid cylinder and a hollow cylinder have the same mass and the same radius. Which statement is true concerning their moment of inertai about an axis through the exact center of the flat surfaces? a. the moment of inertia cannot be determined since it depends on the amount of material from the inside of the hollow cylinder. b. the solid cylinder has the greater moment of inertai c. the hollow cylinder has the greater moment of inertia. d. both cylinders have the same moment of inertia
a
If a constant net torque is applied to an object, that object will a. rotate with constant angular acceleration b. having a decreasing moment of inertia c. rotate with constant linear velocity d. having an increasing moment of inertia e. rotate with constant angular velocity
a
consider a solid object which is subjected to a net torque. That object will experience which of the following? a. an angular acceleration b. a changing moment of inertia c. a linear acceleration and an angular acceleration d. a constant angular velocity
a
the slope of the straight line shown is called the a. Young's modulus b. compressability c. pressure d. bulk modulus
a
two equal forces are applied to a door at the doorknob. The first fore is applied perpendicular to the door, the second force is applied at the 30 degree to the plane of the door. Which force exerts the greater torque? a. the first applied perpendicular to the door b. both exert equal non-zero torques c. both exert zero torques d. the second applied at an angle e. additional information is needed
a
23) A car traveling 20 m/s rounds an 80 m radius horizontal curve with the tires on the verge of slipping. How fast can this car round a second curve of radius 320 m? (Assume the same coefficient of friction between the car's tires and each road surface.) a. 70 m/s b. 40 m/s c. 80 m/s d. 1.6 m/s
b
A heavy boy andn a lightweight girl are balanced on a massless seesaw. If they both moved forward so that they are one-half their original distance from the pivot point, what will happen to the seesaw? a. the side of the girl is sitting on will tilt downward b. nothing, the seesaw will still be balanced c. the side the boy is sitting on will tilt downward d. it is impossible to say without knowing the masses of the children e. it is impossible to say without knowing the values of the original distances
b
A sphereical inflated balloon is submerged in a pool of water. If it is further inflated so that its radius doubles, how is the buoyant force affected? a. 4 times larger b. 8 times larger c. 6 times larger d. not at all e. 2 times larger
b
Air is flowing through a rocket nozzle. Inside the rocket the air has a density of 5.25 kg/m3 and a speed of 1.20 m/s. The interior diameter of the rocket is 15.0 cm. At the nozzle exit, the diameter is 2.50 cm and the density is 1.29 kg/m3. What is the speed of the air when it leaves the nozzle? A) 45.7 m/s B) 123 m/s C) 88.0 m/s D) 29.3 m/s E) 176 m/s
b
An ice skater has a moment of inertia of 5.0 kg∙m2 when her arms are outstretched. At this time she is spinning at 3.0 revolutions per second (rps). If she pulls in her arms and decreases her moment of inertia to 2.0 kg∙m2, how fast will she be spinning? A) 8.4 rps B) 7.5 rps C) 10 rps D) 2.0 rps E) 3.3 rps
b
Does the centripetal force acting on an object do work on the object? a. no, because the object has constant speed b. no, because the force and the displacement of the object are perpendicular c. yes, since a force acts and the object moves, and work is force times the distance d. yes, because the force and the displacement of the object are perpendicular e. yes, since it takes energy to turn an object.
b
Instead of cables, a hydraulic lift raises an elevator weighing 2.5 kiloNewtons. The input piston has a 2.0 cm diameter and the lift piston has a 28. cm diameter (See Fig. 9-3). What minimum force must be applied to the input piston? A) 0.49 MN B) 13. N C) 0.18 kN D) 35. kN E) 2.5 kN
b
Kepler's discovery that T2/r3=K applies a. to lunar motion provided K is the same for planetary motion b. to elliptical orbits where r is the average distance c. to orbits where K is a universal constant d. only to circular orbits
b
Marilyn (M) and her sister Sheila (S) are riding on a merry go round, as shown in Fig. 7-3. Which of the following is true? a. they have the same speed and the same angular velocity. b. they have different speeds, but the same angular velocity c. they have the same speed, but their angular velocity is different. d. they have different speeds, and different angular velocities.
b
a heavy seesaw is out of balance. A lightweight girl sits on the end that is tilted downward, and a heavy boy sits on the other side so that the seesaw now balances. If the boy and girl both move forward so that they are one-hald their original distance from the pivot point, what will happen to the seesaw? a. nothing, the seesaw will still be balanced. b. the side the girl is sitting on will once again tilt downward c. the side of the boy is sitting on will now tilt downward. d. it is impossible to say without knowing the masses of the children. e. it is impossible tosay without knowing the values of the original distances
b
a pencil balanced on its tip such that it does not move a. has a net torque acting on it b. is in unstable equilibrium c. is in stable equilibrium d. has a zero moment of inertia e. has a net vertical force
b
an ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his angular momentum about the axis of rotation? a. it decreases b. it does not change c. it increases d. it changes, but it is impossible to tell which way
b
strain is a. the applied force per unit area b. the ratio of the change in lenth to the original length c. the stress per unit area d. the ratio of stress to elastic modulus
b
stress is a. applied force per cross-secional area b. the same as force c. the strain per unit of strength d. the ratio of the change in length.
b
) A cable is 100-m long and has a cross-sectional area of 1 mm2. A 1000-N force is applied to stretch the cable. The elastic modulus for the cable is 1.0 × 1011 N/m2. How far does it stretch? A) 0.01 m B) 0.001 m C) 1.0 m D) 10 m E) 0.10 m
c
A rock is suspended from a scale reads 20.0 N. A beaker of water is raised up so the rock is totally submerged in the water. The scale now reads 12.5 N. What is the density of the rock? A) 2.33 × 103 kg/m3 B) 3.00 × 103 kg/m3 C) 2.67 × 103 kg/m3 D) 1.60 × 103 kg/m3 E) 2.50 × 103 kg/m3
c
A ship that weighs 10,000 tons (mass 10 million kg) must displace what volume of fresh water in order to float A) B) C) D) E)
c
Consider a rigid body that is rotating. Which of the following is an accurate statement? a. the center of rotation must be moving with a constant velocity b. its center of rotation must be at rest c. all points on the body are moving with the same angular velocity. d. all points on the body are moving with the same linear velocity. e. its center of rotation is its center of gravity
c
The flywheel of a machine is rotating at 126 rad/s. Through what angle will the wheel be displaced from its original position after 6.0 s? a. 7.3*10^2 radians b. 21. radians c. 0.32 revolutions d. 7.3*10^-2 revolutions e. 1.2*10^2
c
The weight that will cause a wire of diameter d to stretch a given distance, for a fixed length of wire, is a. independent of what the length of the wire is b. proportional to d c. proportional to d^2 d. independent of d.
c
a roller coaster car (mass=M) is on a track that forms a circular loop (radius=r) in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point? a. Mrg b. sq rt rg/ sq rt 2 c. sq rt rg d. sq rt 2rg e. 2Mrg
c
which of the following would be expected to have the smallest BULK MODULUS? a. liquid water b. liquid mercury c. helium vapor d. solid uranium e. solid iron
c
66) A 0.600-mm diameter wire stretches 0.5% of its length when it is stretched with a tension of 20 N. What is the Young's modulus of this wire? A) 5.66 × 1010 N/m2 B) 6.43 × 109 N/m2 C) 2.78 × 109 N/m2 D) 1.41 × 1010 N/m2 E) 3.54 × 109 N/m2
d
A mass of 1000 kg hangs at the end of a steel rod 5.0 m in length. The diameter of the rod is 0.80 cm and Young's modulus for the rod is 210,000 MN/m2. What is the elongation of the rod? A) 1.8 cm B) 0.047 cm C) 1.2 cm D) 0.46 cm E) 0.12 cm
d
A planet revolves clockwise around a star, with constant speed, as shown in Fig. 7-1. Which graph shows the direction of the planet's acceleration at point P: graph a, b, c, or d?
d
An ice skater performs a pirouette (a fast spin) by pulling his outstretched arms close to his body. What happens to his rotational kinetic energy about the axis of rotation? a. it changes, but it is impossible to tell which way b. it does not change c. it decreases d. it increases
d
The condition for rolling without slipping is that the center of mass speed is A) Vcm= r B) Vcm = ω C) Vcm = r ω / 2 D) Vcm = r ω E) Vcm = 2 r ω
d
When you are scuba diving, the pressure on your face plate a. will be the greatest when you are facing upward b. is independent of both depth and orientation c. will be greatest when you are facing downward e. depends only on your depth, and not on how you are oriented
d
a ball, a solid cylinder, and a hollow pipe all have equal masses and radii. If the three are released simultaneously at the top of an inclined plane, which will reach the bottom first? a. pipe b. they all reach the bottom in the same time c. cylinder d. ball
d
a seesaw made of a plank of mass 10 kg and length 3 m. is balanced on a fulcrum 1.0 m from one end of the plank. A 20 kg mass rests on the end of the plank nearest the fulcrum. What mass mustbe on the other end if the plank remains balanced? a. 5 kg b. -10 kg c. 6.67 kg d. 7.50 kg e. 10 kg
d
a submarine rests on the sea bottom. The normal force exerted upon the sub by the sea-floor is equal to a. the buoyant force less 1 atmosphere acting on the sub b. the weight of the displaced water c. the weight of the sub plus the weight of the displaced water d. the weight of the sub minus the weight of the displaced water e. the weight of the sub
d
two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob, Both forces are applied perpendicular to the door. Which force exerts the greater torque? a. both exert equal non-zero torques b. both exert zero torques c. the first at the midpoint d. the second at the doorknob e. additional information is needed.
d
) A copper wire is found to break when subjected to minimum tension of 36. N. If the wire diameter were half as great, we would expect the wire to break when subjected to a minimum tension of A) 18 N B) 36. N C) 51. N D) 26. N E) 9.0 N
e
) An incompressible fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is is What is the fluid speed at a location where the diameter has narrowed to A) 0.64 m/s B) 2.56 m/s C) 0.32 m/s D) 1.28 m/s E) 5.12 m/s
e
A 3.00-m long tube with circular crosssection tapers from a diameter of 10.0 cm at one end down to 4.00 cm at the other end. If an incompressible fluid flows irrotationally through the tube at a speed of 2.00 m/s at the 10.0 cm end, what is the speed of the flow at the 4.00 cm diameter end? A) 2.00 m/s B) 0.800 m/s C) 6.25 m/s D) 1.60 m/s E) 12.5 m/s
e
A spherically symmetric planet has four times the Earth's mass and is twice its radius. If a jar of peanut butter weighs 12. N on the surface of the Earth, how much would it weigh on the surface of this planet? a. 30 N b. 18 N c. 6 N d. 24 N e. 12 N
e
The moment of inertia of a solid cylinder about its axis is given by 0.5MRsquared. If this cylinder rolls without slipping, the ration of its rotational kinetic energy to its translational kinetic energy is a. 1:1 b. 1:3 c. 2:1 d. 3:1 e. 1:2
e
a flywheel, a radius of 1 m, is spinning with a constant angular velocity of 2 rad/s. What is the centripetal acceleration of a point on the wheel's rim? a. 6 m/s2 b. 2 m/s2 c. 8 m/s2 d. 1 m/s2 e. 4m/s2
e
a race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience? a. 6.3*10^2 rad/s^2 B) zero C) 2.0 × 1 rad/ D) 1.0 × 1 rad/ E) 1.0 × 101 rad/
e
a thin hoop with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 3.5 rad/s. What is its kinetic energy? a. 0.96 J b. 0.092 J c. 0.53 J d. 1.05 J e. 0.18 J
e
a uniform rod has a weight of 40. N and a length of 1.0 m. It is hinged to a wall (at the left end), and held in a horizontal position by a vertical massless string (at the right end), as shown. What is the magnitude of the torque exerted by the string about a horizontal axis which passes through the hinge and is perpendiuclar to the rod? a. 5 mN b. 10mN c. 30mN d. 40mN e. 20mN
e
consider two uniform solid spheres where both have the same diameter, but one has twice the mass of the other. The ratio of the larger moment of inertia to that of the smaller moment of inertai is a. 8 b. 4 c. 6 d. 10 e. 2
e
