physics quiz review

A ball is thrown horizontally with an initial velocity of 80 m/s from the top of a tower that is 90 m high. What is the horizontal velocity of the ball just before it reaches the ground? a. 80 m/s. b. 9.8 m/s c. 90 m/s d. 0.9 m/s

a

A car of mass m is moving with a momentum p. How would you represent its kinetic energy in terms of these two quantities? a. p2/2m b. pm c. pm/2 d. ½ p2m

a

A copper wire has a length L and cross-sectional area A. What happens to the resistivity of the wire if the length is doubled and cross-sectional area halved? a. Stays the same b. Half as large c. Two times as large d. Four times as large

a

A hollow metal sphere of radius R is positively charged. At which distance would an identically charged sphere experience the greatest electric force? a. R b. 2R c. 3R d. 4R

a

A pilot drops a package from a plane flying horizontally at a speed of 100 m/s. Two seconds later while maintaining that speed the pilot drops a second package. What can you determine from the given information? a. The horizontal distance between the two packages. b. You do not have enough information to determine anything. c. The speed of the packages just before they hit the ground. d. The altitude of the plane.

a

A pilot executes a vertical dive then follows a semi-circular arc until it is going straight up. Just as the plane is at its lowest point, the force of the seat on him is a. more than mg, and pointing up. b. less than mg, and pointing down. c. more than mg, and pointing down. d. less than mg, and pointing up.

a

A plastic rod is rubbed with a piece of wool. During the process the plastic rod acquires a positive charge and the wool: a. acquires an equal negative charge b. acquires a smaller magnitude charge c. acquires an equal positive charge d. remains neutral

a

A roller coaster car is on a track that forms a circular loop in the vertical plane. If the car is to just maintain contact with track at the top of the loop, what is the minimum value for its centripetal acceleration at this point? a. g downward b. 2g downward c. g upward d. 0.5g downward

a

A rubber ball with a mass of 0.25 kg and a speed of 9.0 m/s collides perpendicularly with a wall and bounces off with a speed of 11 m/s in the opposite direction. What is the magnitude of the impulse acting on the rubber ball? a. 5 kg-m/s b. 2 kg-m/s c. 0.5 kg-m/s d. 20 kg-m/s

a

As you stand on the sidewalk waiting for the bus, an ambulance rushes past you, travelling from your left side toward your right side. What is true about the frequency you hear? a. it increases, then decreases b. it is constant c. it decreases constantly d. it increases constantly

a

Frequency refers to a. how many cycles per second occur in a given wave. b. the addition of waves when they interfere with one another. c. the speed change of a wave as it travels from one medium to another. d. how cycles per second are perceived by the human ear.

a

If you hear the pitch of a siren become higher, you know that a. you are moving toward the siren or the siren is moving toward you. b. the source has just passed you or it is accelerating away from you. c. neither you nor the siren is moving. d. you are moving away from the siren or the siren is moving toward you.

a

If you push twice as hard against a stationary brick wall, the amount of work you do a. remains constant at zero. b. quadruples. c. remains constant but non-zero. d. doubles.

a

The graph below shows the velocity of a racecar as it leaves the starting line and travels a linear path. What is the magnitude of the displacement of the car from t = 1.0 s to t = 3.0 s? a. 40 m b. 20 m c. 80 m d. 60 m

a

Two cars, an Alfa Romeo and a Boxster, are 400 m apart on a test track. The Alfa travles due east at 30 m/s while the Boxster travels due west at 20 m/s. How much time passes before the cars collide? a. 8 s b. 13 s c. 40 s d. 20 s

a

You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions? a. It would have skidded 4 times farther. b. It would have skidded twice as far. c. It would have skidded only ½ as far. d. It is impossible to tell from the information given.

a

A heavy box sits at rest on a floor. The forces acting on the box can be represented by which of the following? Choose two answers. a. Non-zero vector pointing up b. Non-zero vector pointing down c. Non-zero vector pointing left d. Non-zero vector pointing right

a,b

Which of the following are characteristics of energy? Choose two answers. a. The amount of energy in an isolated system can be changed by an external force performing work on it. b. Mechanical energy can be changed into thermal energy. c. Thermal energy can never be changed into mechanical energy. d. Energy is only present in an object when it is moving.

a,b

Two marble roll of a table at the same moment. One is traveling at 3 m/s and the other at 5 m/s. The table is 1 m high. Which of the following are true? Choose two answers. a. The marble with the speed of 5 m/s hits the ground first. b. Both marbles have the same acceleration.This answer is correct. c. Both marbles have the same speed as they hit the ground. d. The marble with the speed of 5 m/s will land further than the one with the speed of 3 m/s.

b,d

What two situations have a net non-zero amount of net work? Choose two answers. a. Dragging a wagon across a floor, causing it to accelerate b. Quickly spinning a ball in a circleanswer. c. Sliding a textbook up a ramp with a force of 10N d. Carrying a vase horizontally at a constant speed

b,d

When a student stands on a rotating table, which of the following are true of the frictional force exerted on the student by the table? Choose two answers. a. zero when the table rotates at the constant speed b. equal in magnitude than the frictional force exerted on the table by the student c. greater in magnitude than the frictional force exerted on the table by the student d. directed toward the center of the table e. less in magnitude than the frictional force exerted on the table by the student

b,d

Which of the following graphs represent an object moving toward its reference point? Choose two answers. graph 1 diagonal line graph 2 curves up graph 3 diagonal line coming down graph 4 curves downward a. 1 b. 2. c. 3 d. 4

b,d

Which of the following is true for a system consisting of a pendulum swinging in simple harmonic motion? a. The maximum kinetic energy occurs at maximum displacement of the mass from its equilibrium position. b. The maximum potential energy is achieved when the bob passes through its equilibrium position. c. The kinetic and potential energies are both constant. d. The maximum kinetic energy and maximum potential energy are equal, but occur at different times.

d

Which of the following occur as a wave encounters a free-end boundary? a. The wave is reflected and inverted. b. Nothing - the wave is absorbed by the boundary. c. The wave is inverted but not reflected. d. The wave is reflected but not inverted.

d

A 3-kg ball is dropped onto a concrete floor. What is the magnitude of the ball's change in momentum if its speed just before striking the floor is 7 m/s and its rebound speed is 3 m/s? a. 60 kg-m/s b. 30 kg-m/s c. 10 kg-m/s d. 15 kg-m/s

b

A 4 kg ball is attached to a 1.5 m long string and whirled in a horizontal circle at a constant speed of 5 m/s. How much work is done on the ball during one period? a. 9 J b. 0 J c. 4.5 J d. 2 J

b

A ball is thrown and follows the parabolic path shown below. Air friction is negligible. Point Q is the highest point on the path. Points P and R are the same height above the ground. How do the speeds of the ball at the three points compare? a. vR < vQ < vP b. vQ< vP = vR c. vP = vR < vQ d. vp < vQ < vR

b

A child whirls a ball at the end of a rope, in a uniform circular motion. Which of the following statements is NOT true? a. The radius is constant b. The velocity of the ball is constant. c. The speed of the ball is constant. d. The magnitude of the ball's acceleration is constant. e. The acceleration of the ball is directed radially inwards, toward the center of its path.

b

A penny is resting on a turntable. What is the force acting as the centripetal force keeping the penny rotating with the turntable? a. Gravitational force b. Frictional force c. Tension force d. Normal force

b

A projectile is launched with an initial velocity v at an angle theta above the horizontal. What is the magnitude of the horizontal component of the projectile's initial velocity? a. theta cos(v) m/s b. vcos(theta) m/s Selected: c. vsin(theta) m/s d. theta sin(v) m/s

b

A record on a turntable is spinning and coming to rest. At t = 0 s, the angular velocity of the record is 20.0 rad/s with a constant acceleration of - 5.0 rad/s2. What is the record's angular displacement at t = 2.0 s? a. 15 rad b. 30 rad c. 40 rad d. 50 rad

b

A uniform rope is attached to a hook as shown below. A box of weight 100 N is attached to the rope. What is the tension in the rope? a. 0 N b. 100 N c. 1000 N d. 10 N

b

An elevator car weighs 5500 N. If the car accelerates upwards at a rate of 4.0 m/s2, what is the tension in the support cable lifting the car? Use g = 10 m/s2. a. 3300 N b. 7700 N c. 4400 N d. 1600 N

b

An object of weight W is suspended from the center of a massless string as shown below. The tension (FT) at any point in the string is: mc004-1.jpg a. 2Wsin theta b. W/2cos theta c. 2Wcos theta d. 1/2 Wsin theta

b

If you are standing somewhere between two speakers that are emitting the exact same sound waves, but you hear no sound, which of the following is true? a. The sound waves are constructively interfering with one another. b. The sound waves are destructively interfering with one another. c. The speakers are pointed away from you. d. One speaker must not be emitting any sound waves.

b

Starting from the origin, a person walks 8 km east during first day, and 5 km west the next day, as shown. What is the net displacement of the person from the initial point in two days? a. 10 km, west b. 3 km, east c. 11 km, east d. 5 km, west

b

The Earth pulls down on a grapefruit with an action force of 1.96 N. Which of the following is the reaction force? a. The grapefruit pulls down on the Earth with 1.96 N b. The grapefruit pulls up on the Earth with 1.96 N c. The grapefruit pushes down on the Earth with 1.96 N d. The grapefruit pushes up on the Earth with 1.96 N

b

Two isolated charges, + 2q and -5q, are 2 centimeters apart. If F is the magnitude of the force acting on charge -5Q, what are the magnitude and direction of the force acting on charge + 2q ? Magnitude Direction (A) 2 F Away from charge -5q (B) F Toward charge -5q (C) F Away from charge -5q (D) 2F Toward charge -5q a. A b. B c. C d. D

b

Which of the following has the lowest speed of sound? a. copper at 0°C b. air at 0°C c. air at 100°C d. water at 0°C

b

A kickball is rolled by the pitcher at a speed of 10 m/s and it is kicked by another student. The kickball deforms a little during the kick, and then rebounds with a velocity of 15 m/s as its shape restores to a perfect sphere. What must be true about the kickball and the kicking foot system? Choose two answers. a. The kinetic energy of the system before and after the kick is the same. b. The momentum of the system before and after the kick is the same.. c. The kinetic energy of the system before and after the kick is not the same. d. The momentum of the system before and after the kick is not the same.

b,c

A meteor of mass, M moves with a constant speed, v in a circular orbit of radius R. Which of the following statements are true? Choose two answers. a. Its angular momentum is not constant. b. The magnitude of the centripetal acceleration is constant. c. The tangential acceleration is zero. d. The tangential acceleration is a constant, non zero value.

b,c

A red ball and a green ball are simultaneously thrown horizontally from the same height. The red ball has an initial speed of 40 m/s and the green ball has an initial speed of 20 m/s. Which of the following is true regarding the flight of the green ball and the red ball? Choose two answers. a. The red ball and the green ball will travel equal distances horizontally. b. The red ball will travel twice as far horizontally compared to the green ball.This answer is correct. c. The red ball and the green ball take equal amounts of time to land.This answer is correct. d. The red ball takes twice as much time to land compared to the green ball.

b,c

A ball attached to a string is whirled around in a horizontal circle having radius r. If the radius of the circle is changed to r/4 and the same centripetal force is applied by the string, the new speed of the ball is which of the following. a. Four times the original speed b. One-quarter of the original speed c. One-half of the original speed d. Twice the original speed

c

A deliveryman moves 10 cartons from the sidewalk, along a 10-meter ramp to a loading dock, which is 1.5 meters above the sidewalk. If each carton has a mass of 25 kg, what is the total work done by the deliveryman on the cartons to move them to the loading dock? a. 2500 J b. 37500 J c. 3750 J d. 25000 J

c

A group of cyclists took a four-hour trip. During the first three hours, the travelled a total of 50 km, but during the last hour, they only travelled 10 km. What waht the group's average speed for the entire trip? a. 30 km/h b. 60 km/h c. 15 km/h d. 40 km/h

c

A mass-spring oscillating system undergoes SHM with a period T. What is the period of the system if the amplitude is tripled? a. T/3 b. 3T c. T d. 6T

c

An ice skater performs a fast spin by pulling her outstretched arms down and close to her body. What happens to her kinetic energy? a. depends on her initial rotational velocity b. stays the same c. increases

c

If the net work done on an object is zero, then the object's kinetic energy a. is zero. b. increases. c. remains the same. d. decreases.

c

Question 3 As shown below, a ball is thrown straight up from point A. It reaches a maximum height at point B, then falls back to point C. Which of the following is true about the direction the ball's velocity and acceleration between A and B? a. v and a down b. v and a up c . v up a down d. v down a up

c

The frequency of a wave traveling in a string is quadrupled. Which of the following is true about the wave's speed? a. It doubles b. It halves c. it stays the same d. It quadruples

c

The two spheres above have equal densities and are subject only to their mutual gravitational attraction. Which of the following quantities must have the same magnitude for both spheres? a. Acceleration b. Kinetic Energy c. Gravitational Force d. Velocity

c

Which is not true of a solid sphere rolling down a hill? a. It has translational kinetic energy. b. It has rotational kinetic energy. c. It experiences zero torques. d. It has changing angular momentum.

c

Billy throws a stone upward at an angle of 45o. Which statements best describe the stone at the highest point that it reaches? Choose two answers. a. Its horzontal velocity is zero. b. Its vertical acceleration is zero. c. Its horizontal acceleration is zero.This answer is correct. d. Its vertical velocity is zero.

c,d

"Dead spots" in a theater are an example of a. beats. b. resonance. c. constructive interference. d. destructive interference.

d

A horizontal force F is used to pull a 5 kg block across a floor at a constant speed of 3 m/s. The frictional force between the block and the floor is 10 N. The work done by the force F in 1 minute is most nearly: a. 22.5 J b. 600 J c. 0 J d. 1,800 J

d

A passenger who is standing and facing forward in a moving train suddenly falls backward. This can be an indication of which of the following? a. The train slows down. b. The train turns to the right. c. The train doesn't change its speed. d. The train speeds up.

d

A pickup truck is being driven down the highway carrying a 100 gallon fish tank full of water. A hole is punctured in the tank and the water flows out of the tank and truck to the ground. If the driver maintains the same pressure on the gas pedal, and the road stays flat and level, what happens to the velocity of the truck and which conservation law applies? a. Increases; Conservation of Kinetic Energy b. Decreases; Conservation of Kinetic Energy c. Decreases; Conservation of Momentum d. Increases; Conservation of Momentum

d

A small sphere is moving in a vertical circle at constant speed. The magnitude of the net force on the sphere a. increases as the sphere moves from the bottom to the top. b. at the bottom of the loop is greater than the net force at the top. c. at the top of the loop is greater than the net force at the bottom. d. is the same at the top of the loop as it is at the bottom of the loop.

d

An apple falls from a tree off of a cliff. How fast is the apple travelling after it falls 4.9 m, if it accelerates at 9.8 m/s2? a. 96 m/s b. 24 m/s c. 4.9 m/s Selected: d. 9.8 m/s

d

Object 1 travels north with a momentum of 55 kg-m/s. Object 2 travels west with a momentum of 33 kg-m/s. The two objects collide and stick together. What is the momentum of the two objects (magnitude and the angle they make with the east-west axis) after the collision? a. 58 kg-m/s; 59º b. 64 kg-m/s; 31º c. 60 kg-m/s; 31º d. 64 kg-m/s; 59º

d

The distance between two identical charges is halved, the magnitude of the force between them a. is halved. b. is quartered c. is doubled. d. is quadrupled

d

The kinetic energy of a moving bicycle is quadrupled. Which of the following could happen to its momentum? a. It doubles b. It halves c. It decreases to 1/4 d. It quadruples

d

Which of the following is the region of a longitudinal wave in which the density and pressure are lower than normal? a. Doppler effect b. compression c. spherical wave d. rarefaction

d