Physics 2A final

If two forces of equal magnitude act on an object that is hinged at a pivot, the force acting farther from the pivot must be produce the greater torque about the pivot.

False

Water flows through a pipe having a varying width. More water flows per second through the wide section than through the narrow section because there is more room for it to flow.

False

Observer A is 2.0 m from a tiny light bulb and observer B is 8.0 m from the same bulb. The intensity of light from this bulb that A sees is 16 times as great as the intensity that B sees.

True

An object is attached to a vertical ideal massless spring and bobs up and down between the two extreme points A and B. When the kinetic energy of the object is a minimum, the object is located

at either A or B

Momentum will be conserved in a two-body collision only if

the net external force acting on the two-body system is zero.

The slope of a position vs time graph gives

velocity

If the forces on an object balance, it does not necessarily follow that the torques balance.

True

Which of the following situations is impossible?

An object has constant non-zero velocity and changing acceleration

Under what conditions is average velocity equal to the average of the object's initial and final velocity?

The acceleration is constant

Which one of the following statements concerning the buoyant force on an object submerged in a liquid is true?

The buoyant force depends on the volume of the liquid displaced.

Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.

The displacement is either less than or equal to the distance traveled.

If an object is stretched beyond its elastic limit, it does not return to its original length upon removal of the external force.

True

isobaric

happens at constant pressure

While in Earth's orbit, an 80 kg astronaut carrying a 20kg tool kit is initially drifting toward a stationary (relative to her) space shuttle at a speed of 2m/s. If she throws the toolkit toward the shuttle with a speed of 6 m/s as seen from the shuttle, her final speed is

1 m/s towards the shuttle

Two blocks of masses 2m and m are in contact on a horizontal frictionless surface. If a force F is applied to mass 2m, what is the force on mass m?

1/3 F

Two blocks rest on a horizontal frictionless surface. The surface between the top and bottom blocks is roughened so that there is no slipping between the two blocks. A 30-N force is applied to the bottom block. What is the acceleration of the "two block" system?

2m/s^2

A 615 N student standing on a scale in an elevator notices that the scale reads 645 N. From this information, the student knows that the elevator must be moving upward.

False

A mass is oscillating at the end of a spring. Neither the period of oscillation nor the maximum speed of the mass depends on the amplitude of the motion

False

A rubber ball moving horizontally at 8.50 m/s hits a brick wall and bounces back with exactly the same speed but in the opposite direction. During this collision, its change in momentum is zero

False

According to Pascal's principle, if you increase the pressure enough so that the force at one end of an oil-filled tube increases by 10 N, the force will increase at all points in the tube by 10 N.

False

If the fourth harmonic for a string fixed at both ends is 200 Hz, the fundamental frequency for this string is 880 Hz

False

If two objects have the same moment of inertia, they must have the same mass.

False

A spinning star begins to collapse under its own gravitational pull. Which of the following occurs as the star becomes smaller?

Its angular momentum remains constant

For general projectile motion, when the projectile is at the highest point of its trajectory

Its velocity is perpendicular to the acceleration

Which of the following is an accurate statement?

The ratio stress/strain is called the elastic modulus

A donkey pulls a crate up a rough, inclined plane at constant speed. Which one of the following statements concerning this situation is false

The work done on the object by gravity is zero jules

Two objects are thrown from the top of a tall building and experience no appreciable air resistance. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?

They are traveling at the same speed.

A wave pulse moves along a uniform string. The speed of this wave is constant but the speed of the particles of the string change with time.

True

If you double the mass of the pendulum, the period of vibration does not change

True

Simple harmonic motion occurs only if the restoring force is directly proportional to the first power of the displacement.

True

Archimedes Pinciple

a fluid exerts an upward buoyant force on an object immersed in or floating on the liquid. The magnitude of the buoyant force equals the weight of the fluid displaced by the object

An object is moving with constant nonzero velocity in the +x direction. The velocity vs time graph of this object is

a horizontal straight line

An object is moving with constant nonzero acceleration in the +x direction. The position vs time graph of the object is

a parabolic curve

A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rocks hits the floor

exactly below the midpoint of the ceiling.

isothermal

happens at constant temp

constant-volume process

has no change in volume

Complete the following statement: A body is in a state of equilibrium

if it is at rest or moving with constant velocity.

adiabatic

involves no transfer of heat, the temp changes

When a ball is thrown straight up with no air resistance, the acceleration at its highest point

is downward

thermal expansion

objects experience an increase in volume and an increase in length when their temp changes

A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on large, air-filled bag. Which of the following 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 stalled car is being pushed up a hill at a constant velocity by three people. The net force on the car is

zero