Physics 1943 MAYER

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

False

In order to lift a bucket of concrete, you must pull up harder on the bucket than it pulls down on you.

False

A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii and are of uniform density. If the three are released simultaneously at the top of an inclined plane and roll without slipping, which one will reach the bottom first?

Solid sphere

When an object is solely under the influence of conservative forces, the sum of its kinetic and potential energies does not change.

True

Swimmers at a water park have a choice of two frictionless water slides as SHOWN IN THE FIGURE. Although both slides drop over the same height, h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the end of slide 1 (straight) compares with v2, the speed of the swimmer reaching the end of slide 2 (curved)?

v1=v2

If the acceleration of an object is negative, the object must be slowing down.

False

During which of the five segments of the job does the stock person do positive work on the boxes? 1) Picking up the boxes of tomatoes from the stockroom floor 2) Accelerating to a comfortable speed 3) Carrying the boxes to the tomato display at constant speed 4) Decelerating to a stop 5) Lowering the boxes slowly to the floor

1) and 2)

When a rigid body rotates about a fixed axis, all the points in the body have the same:

Angular acceleration.

A pilot drops a package from a plane flying horizontal at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will:

Be over the package.

In a collision between two objects having unequal masses, how does magnitude of the impulse imparted to the lighter object by the heavier one compare with the magnitude of the impulse imparted to the heavier object by the lighter one?

Both objects receive the same impulse.

A 4.0kg object is moving with speed 2.0m/s. A 1.0kg object is moving with speed 4.0m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

Both objects travel the same distance.

Ina perfectly ELASTIC collision between two perfectly rigid objects:

Both the momentum and the kietic energy of the system are conserved.

As the speed of a moving fluid increases, the pressure in the fluid

Decreases.

As you are leaving a building, the door opens outward. If the hinges on the door are on your right, what is the direction of the angular velocity of the door as you open it?

Down. (Right hand rule)

You swing a bat and hit a heavy box with a force of 1500N. The force the box exerts on the bat is:

Exactly 1500N whether or not the box moves.

A restoring force of magnitude F acts on a system with a displacement of magnitude x. In which of the following cases with the system undergo simple harmonic motion?

F is proportional to x

A dumbbell-shaped object is composed by two equal masses, m, connected by a rod of negligible mass and length r. If I1 is the moment of inertia of this object with respect to an axis passing through the center of the rod and perpendicular to it and I2 is the moment of inertia with respect to an axis passing through one of the masses, it follows that

I2>I1

Consider a uniform solid sphere of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or rotational kinetic energy?

Its translational kinetic energy is larger than its rotational.

Salt water is more dense than fresh water. A ship floats in both fresh water and salt water. COmpared to the volume of fresh water displaced by the ship, the volume of salwater displaced by the ship is:

Less than the volume of fresh water.

A brick is resting on a rough incline. The friction force acting on the brick, along the incline, is:

Less than the weight of the brick.

A 32-kg child and a 25-kg child are balanced on a massless seesaw. If they both move forward so that they are each one-half their original distance from the pivot point, what will happen to the seesaw? Assume that both children are small enough compared to the length of the seesaw to be thought of as point of masses.

Nothing will happen; the seesaw will still be balanced.

In what situation can we be certain that the average velocity of an object is equal to its instantaneous velocity at every time?

Only when the velocity is constant.

A mass M is attached to an ideal massless spring. When this system is set in motion with amplitude A, it has a period T. What is the period if the amplitude of the motion is increased to 2A?

T.

A box of mass m is pulled with a constant acceleration a along a horizontal frictionless floor by a wire that makes an angle of 15 degrees above the horizontal. If T is the tension in this wire, then:

T>ma

If a force always acts perpendicular to an object's direction of motion, that forcec cannot change the object's kinetic energy.

True

A simple pendulum on the surface of the earth has a period of 1.00s. On a distant planet, the length of the pendulum must be shortened slightly to have a period of 1.00s. What is true about the acceleration due to gravity on the distant planet?

The gravitational acceleration on the planet is slightly less than g.

Two objects, one fo mass m and the other of mass 2m, are dropped from the top of a building. When they hit the ground:

The heavier one will have twice the kinetic energy of the lighter one.

While an object is in projectile motion (with upward being positive) with no air resistance,

The horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to -g.

A 50-cm^3 block of wood is floating partially submerged in water, and a 50-cm^3 block of iron is totally submerged in water. Which block has the greater bouyant force on it?

The iron.

A horizontal disk rotates about a vertical axis through its center. Point P is midway between the center and the rim of the disk, and point Q is on the rim. If the disk turns with constant angular velocity which of the following statements about it is true?

The linear velocity of Q is twice as great as linear velocity of P.

In simple harmonic motion, the speed is greatest at that point in the cycle when

The magnitude of the acceleration is a minimum.

A shell explodes into two fragments, one fragment 25 times heavier than the other. If any gas from the explosion has negligible mass, then:

The momentum change of the lighter fragment is exactly the same as the momentum change of the heavier fragment.

In an INELASTIC collision between two objects:

The momentum of the system is conserved but the kinetic energy of the system is not conserved.

At a certain depth in the ocean, the pressure is p. If you go to twice that depth (treating the water as in-compressible):

The pressure will be less than 2p

A small car has a head-on collision with a large truck. Which of the following statements concerning the magnitude of the average force due to the collision is correct?

The small car and the truck experience the same average force.

Jan and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Jan drops her rock straight down. Len throws his rock straight out horizontally. If air resistance is negligible, which rock hits the ground first?

They hit at the same time.

When you ride a bicycle, in what direction is the angular velocity of the wheels?

To the left.

FOr an object in uniform circular motion, its velocity and acceleration vectors are always perpendicular to each other at every point in the path.

True

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

Upward

A box slides down a frictionless plane inclined at an angle of 30 degrees above the horizontal. The gravitational force on the box is directed:

Vertically.

The angular momentum of a system remains constant:

When no torque acts on the system.

A stalled car is being pushed up a hill at constant velocity by three people. The net force on the car is:

Zero.