Foreign Policy

T

A 10-kg rock and 20-kg rock are dropped from the same height and experience no significant air resistance. If it takes the 20-kg rock a time T to reach the ground, what time will it take the 10-kg rock to reach the ground?

h

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0 and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?

Its velocity points upward and its acceleration points downward

A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?

Equal to the weight of the bucket

A bucket is being lowered by a very light rope with a constant downward velocity. The tension in the rope must be

Perpendicular to the curve inward

A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road?

Be directly over the package

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

Is half as much as before

A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system

The ball

A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change?

Greater than

A small car collides with a large truck. Is the acceleration experienced by the car greater than, less than, or equal to the acceleration experienced by the truck?

A straight line making an angle with the time axis

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is

A straight line making an angle with the time axis

An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is

A horizontal straight line

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is

The vectors are perpendicular to each other

An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.

Parabolic, the parabola opens downward (inverse U-shaped)

An object moves with a constant, negative acceleration. What is the shape of the position-time graph?

Both vehicles experience the same magnitude of force, therefore the lightweight car experiences the greater acceleration

Choose the best explanation from among the following

Is always zero

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration

Velocity is a vector, whereas speed is a scalar and speed does not include any information about direction of travel, but velocity does

How are speed and velocity different?

Each has the same dimensions (length/time) and each is used to describe the motion of objects

How are speed and velocity similar?

True

If A −B =0, then the vectors A and B have equal magnitudes and are directed in the same direction.

False

If a vector's components are all negative, then the magnitude of the vector is negative.

At rest

If the position versus time graph of an object is a horizontal line, the object is

Power

If the units of your answer are kg • m2/s3, which of the following types of quantities could your answer be? (There could be more than one correct choice.)

Moving with constant non-zero acceleration

If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is

No

Is it possible for the kinetic energy of an object to be negative?

Exactly g

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?

Its acceleration is in the -x direction

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

The acceleration is equal to zero

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?

True

The magnitude of a vector can never be less than the magnitude of any of its components

Positive

The position-time graph for an object moving with constant acceleration starts off with zero slope. At later times the slope is positive. Is the acceleration of the object positive, negative, or zero?

Zero

The position-time graph for an object moving with constant acceleration starts off with zero slope. At later times the slope is positive. Is the initial velocity of this object positive, negative, or zero?

Velocity

The slope of a position versus time graph gives

Acceleration

The slope of a velocity versus time graph gives

32F

Two small objects, with masses m and M, are originally a distance r apart, and the gravitational force on each one has magnitude F. The second object has its mass changed to 2M, and the distance is changed to r/4. What is the magnitude of the new gravitational force?

F/4

Two small objects, with masses m and M, are originally a distance r apart, and the magnitude of the gravitational force on each one is F. The masses are changed to 2m and 2M, and the distance is changed to 4r. What is the magnitude of the new gravitational force?

The acceleration is zero

What is the acceleration of an object whose position-time graph is a straight line?

The friction force from the road

When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path?

Is directed toward the center of its circular path

When an object moves in uniform circular motion, the direction of its acceleration is

N • s and kg • m/s

Which of the following quantities are units of impulse?

The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.)

Moves along a straight-line path in its original direction

You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it

True

Your favorite uncle makes this statement: "A force that is always perpendicular to the velocity of a particle does no work on the particle."