Physics

Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change?

The force will be nine times as great

A rubber ball is dropped from rest from a height h. The ball bounces off the floor and reaches a height of 2h/3. How can we use the principle of the conservation of mechanical energy to interpret this observation?

Work was done on the ball by non-conservative forces that resulted in the ball having less total mechanical energy after the bounce

Six identical bricks are stacked on top of one another. Notes 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?

Yes, this is possible as long as the combined center of gravity of blocks above a given brick does not extend beyond the right side of the brick below

Some children are practicing catching baseballs. The coach tosses the ball into the air and hits the ball with his bat. The ball travels nearly horizontally, directly at the short stop who manages to catch the line drive. Did the coach, via the bat, do any work on the ball as it was hit?

Yes, work was done on the ball because during the time the force acted on the ball, the bat and ball moved through some distnace

A water balloon is dropped from a third story balcony. The balloon burst when it hits the ground. It is a completely inelastic collision with the earth. How much kinetic energy is transferred to the earth as a result of the collision?

Zero joules

After an ice storm, ice falls from one of the top floors of a 65-story building. The ice falls freely under the influence of gravity. Which one of the following statements concerning this situation is true?

The KE of the ice increases by equal amounts for equal distances

For an object undergoing simple harmonic motion

The acceleration is greatest when the displacement is greatest

A small asteroid collides with a planet. Which one of the following statements concerning what happens during the collision is correct?

The asteroid exerts the same amount of force on the planet as the planet exerts on the asteroid

The following plot illustrates how an object's velocity changes with time

The average momentum of this object is constant

A truck drives due south for 1.2 km in 1.5 minuets. Then, the truck turns and drives due west for 1.2 km in 1.5 minutes. Which one of the following statements is correct?

The average speed for the two segments is the same. The average velocity for the two segments is NOT the same.

A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on a large, air-filled bag. Which one of the following best describes why no injury occurs?

The bag increases the amount of time during which the momentum is changing and reduces the average force on the person

A ball is thrown toward a wall, bounces, and returns to the thrower with the same speed as it had before it bounced. Which one of the following statements correctly describes this situation?

The ball was accelerated during its contact with the wall because its direction changed.

An astronaut drops a golf ball that is initially at rest from a cliff on the surface of the moon. The ball falls freely under the influence of gravity. Which one of the following statements is true concerning the ball as it falls? Neglect any frictional effects.

The ball will gain equal amounts of momentum during each second.

By convention, the angular displacement

is positive if it is counterclockwise and negative if it is clockwise

How are frequency and period related in simple harmonic motion?

They are inversely related

Packages A and B are dropped from the same height simultaneously. Package A is dropped from an airplane that is flying due east at constant speed. Package B is dropped from rest from a helicopter hovering in a stationary position above the ground. Ignoring air friction effects, which of the following statements is true?

A and B reach the ground at the SAME time; and they have SAME velocity in the vertical direction.

Complete the following statement: In general stress refers to

A force per unit area

The meteor's orbit changes so that it moves in an elliptical orbit. As it moves from point A to point B, which of the following is true about its speed and angular momentum?

Speed: Decreases Angular Momentum: Remains constant

In which of the following situations is linear momentum not conserved?

A tree limb is struck by lighting and falls to the ground

If an object is moving can you conclude there are forces acting on it? If an object is at rest, can you conclude there are no forces acting on it? Consider each of the following situations. In which one of the following cases, if any, are there no forces action on the object?

Forces are acting on all of the objects in choices a, b, c, and d.

A car travels at constant speed v up a hill from point A to point B, as shown in the diagram below. As the car travels from A to B, its gravitational PE

Increases and it kinetic energy remains the same

What is newtons 2nd law?

F=ma

An airplane starts from rest at the end of a runway and accelerates at a constant rate. In the first second, the airplane travels 1.11m. What is the speed of the airplane at the end of the second second?

4.44 m/s

A bicycle travels 141m along a circular track of radius 15m. What is the angular displacement in radians of the bicycle from its staring position?

9.4 rad

A pendulum swings through a total of 28. If the displacement is equal on each side of the equilibrium position, what is the amplitude of this vibration?

14

What is the fewest number of nodes a standing wave can have?

2

Tripling the displacement from equilibrium of an object in simple harmonic motion will change the magnitude of the object's maximum acceleration by what factor?

3

What is newtons 1st law?

An object in motion will remain in motion unless it is acted on by another force

What is newtons 3rd law?

Any action can have an equal and opposite reaction

A toy rocket is launched at an angle of 45 with a speed of v0. If there is no air resistance, at what point during the time that is in the air does the speed of the rocket equal 0.5v?

At no time during the flight

Three vector A, B, and C, add together to yield to zero: A+B+C=0. The vectors A and C point in opposite directions and their magnitudes are related by the expression: A=2C. Which one of the following conclusions is correct?

B and C have equal magnitudes and point in the same direction

An airplane starts from rest at the end of a runway and begins accelerating. The tires of the plane are rotating with an angular velocity that is uniformly increasing with time. On one of the tires, Point A is located on the part of the tire in contact with the runway surface and point B is located halfway between Point A and the axis of oration. Which one of the following statements is true concerning this situation?

Both points have the same instantaneous angular velocity

Two points are located on the rigid wheel that is rotating with decreasing angular velocity about a fixed axis. Point A is located on the rim of the wheel and point B is halfway between the rim and the axis. Which one of the following statements concerning this situation is true?

Both points have the same instantaneous angular velocity

A car travels at constant speed v up a hill from point A to point B, as shown in the diagram below. As the car travels from A to B, its KE

Decreases and its potential energy increases

Vibration of an object about an equilibrium point is called simple harmonic motion when the restoring force is proportional to

Displacement

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?

Doubling the length or doubling the force will have the same result, but doubling the length is easier

Which of the following statements concerning the moment of inertia I is false?

I depends on the angular acceleration of the object as it rotates

In an air race, two planes are traveling due east. Plane One has a larger acceleration than Plane Two. Both accelerations are in the same direction. Which of the following statements is true concerning this situation?

In the same time interval, the change in the velocity of the Plane One is greater than that of Plane Two

A meteor of mass M moves with constant speed v in circular orbits of radium R. Which of the following statements are true?

Its angular speed is v/R Its tangential acceleration is zero The magnitude of its centripetal acceleration is constant

How does the translational kinetic energy compare to rotational kinetic energy?

Ke without friction is greater than Ke wit friction

Which one of the following choices represents the largest KE?

Mars is moving in its orbit around the Sun

Does the air exert a buoyant force on my pen if I throw it across the room?

NO

A ball is thrown downward and its speed is v just before it strikes the ground. After the collision with the earth, it heads upward with a speed v. Which one of the following statements concerning this situation is true?

Only the momentum of the earth is changed by the collision

The meteor's orbit changes so that it moves in an elliptical orbit, As it moves from point A to point B, which of the following is true about its speed and angular momentum?

Speed- Decreases Angular Momentum- Remains constant

A racecar is traveling at constant speed around a circular track. What happens to the centripetal acceleration of the car is the speed is doubled?

The centripetal acceleration increases by a factor of 4

Which one of the following properties could not be used as a temperature sensitive property in the construction of a thermometer?

The change in mass of a solid

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?

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.

If the ball is replaced with a disk of rotational inertia (1/2)MR^2, how will the velocity at the bottom change?

The disk will travel slower

Which of the following quantities is a vector quantity?

The earth's pull on your body

A sled of mass m is coasting at a constant velocity on the ice covered surface of a lake. Three birds, with a combined mass 0.5m, gently land at the same time on the sled. The sled and birds continue sliding along the original directional motion. How does the kinetic energy of the sled and birds compare with the initial kinetic energy of the sled before the birds landed?

The final kinetic energy is one third of the initial kinetic energy

Object A is traveling due north while object B is traveling due south along the same line. The two objects have a head-on collision. Which one of the following statements best describes the velocities of the objects after the collision?

The final velocities of A and B could be equal to zero m/s

An object is moving due south at a constant velocity. Then, a net force directed due west acts on the object for a short time interval, after which, the net force on the object is zero newtons. Which of the following statements concerning the object is necessarily true?

The final velocity of the object will be directed south of west

Which of the following situations involves a vector?

The flock of Canadian Geese was spotted flying due south at 5 m/s

A ball is rolling down one hill and up another as shown. Points A and B are at the same height. How do the velocity and acceleration change as the ball rolls from point A to point B?

The horizontal component of the velocity is the same at points A and B, but the vertical component of the velocity has the same magnitude, but the opposite sign at B. The acceleration at points A and B is the same.

The two dams are identical with the exception that the water behind dam A extends twice the horizontal distance behind that of dam B. Which of the following statements regarding these damns is correct?

The horizontal distance of the water behind the two dams does not determine the force on them

Two identical balls are thrown from the same height from the roof of a building. One ball is thrown upward with an initial speed v. The second ball is thrown downward with the same initial speed v. When the balls reach the ground, how do the kinetic energies of the two balls compare?

The kinetic energies of the two balls is the same

Two balls of equal size are dropped from the same height from the roof of a building. One ball has twice the mass of the other. When the balls reach the ground, how do the kinetic energies of the two balls compare?

The lighter one has half as much kinetic energy as the other does

Which statement best explains why the weight of an object of mass m is different on Mars than it is on Earth?

The masses and radii of Mars and Earth are not the same

A tennis ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward. Which statement is true concerning this situation?

The momentum of the ball and the momentum of the earth both change

An airplane is flying horizontally at a constant velocity when a package is dropped from its cargo bay. Assuming no air resistance, which one of the following statements is correct?

The package follows a curved path, but it is always vertically below the airplane

A rock is dropped from a high tower and falls freely under the influence of gravity. Which one of the following statements concerning the rock as it falls is true?

The rock will gain an equal amount of momentum during each second

A rigid body rotates about a fixed axis with a constant angular acceleration. Which one of the following statements is true concerning the tangential acceleration of any point on the body?

The tangential acceleration depends on the change in angular velocity

If a system is in thermal equilibrium, during a phase change

The temperature of the mixture does not change

Two identical ping-pong balls are selected for a physics demonstration. A tiny hold is drilled in one of the balls; and the ball is filled with water. The hole is sealed so that no water can escape. The two balls are then dropped from rest at the exact same time from the roof of a building. Assuming there is no wind, which one of the following statements is true?

The two balls reach the ground at the same time

Which two forces form an "action-reaction" pair that obeys Newton's third law?

The weight of the student & the force of the student pulling on the earth

A mountain climber pulls a supply pack up the side of a mountain at a constant speed. Which one of the following statements concerning this situation is false?

The work done on the pack by gravity is zero joules

One common physical parameter of an object that related temperature to the thermal energy?

Velocity of atoms constituting the object

If both the mass m of a simple pendulum and its length L are doubled, the period will

increase by a factor of 1.4

Complete the following statement: In order to increase the frequency of the motion, one would have to

decrease the mass of the block on the end of the spring

The property that most determines whether or not an object will float in oil in the objects?

density

A girl is sitting on the edge of a merry-go-round at a playground as shown. Looking down from above, the merry-go-round is rotating clockwise. What is the direction of the girl's angular velocity?

downward

Consider a mass hanging vertically from a spring at equilibrium. If you pull down by 2cm and release it, it beings to oscillate at a frequency f1. If you had pulled it down instead by 4cm, what would its frequency of oscillation be?

f1

For a system in simple harmonic motion, which of the following is the time required to complete a cycle of motion?

period

The heat that must be supplied or removed to change the temperature of a substance is termed as

specific heat capacity

For an object undergoing simple harmonic motion.

the acceleration is greatest when the displacement is greatest

Why does a duck float?

the duck has feathers

The buoyant force on an object submerged in a fluid depends on

the fluids density & the acceleration due to gravity NOT the objects density

Which force is responsible for holding a car in an unbanked curve?

the force of friction

The buoyant force on an object is dependent on

the submerged volume of the object

Complete the following statement: A collision is elastic if

the total kinetic energy is conserved

An object is placed in fluid. The buoyant force on the object is proportional to

the volume of the object & the density of the fluid

Two identical cares were involved in a collision at an icy intersection. Car A was stopped at a traffic light. Car B was moving at a speed v, when its suffered a perfectly inelastic collision with the back end of car A. With what speed did the two cars slide into the intersection after the collision?

v/2