Mastering Physics 4

It could be moving to the left, moving to the right, or be instantaneously at rest.

A block of mass 2kg is acted upon by two forces: 3N (directed to the left) and 4N (directed to the right). What can you say about the block's motion? It must be moving to the left. It must be moving to the right. It must be at rest. It could be moving to the left, moving to the right, or be instantaneously at rest.

Gravity

A downward force of magnitude 5 N is exerted on the book by the force of the table gravity inertia

moving with a constant nonzero acceleration

A massive block is being pulled along a horizontal frictionless surface by a constant horizontal force. The block must be __________. continuously changing direction moving at constant velocity moving with a constant nonzero acceleration moving with continuously increasing acceleration

a contact force

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. The force acting on the block and directed to the left is __________. a contact force a long-range force

a contact force

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. The force acting on the block and directed to the right is __________. a contact force a long-range force

friction

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. What is the force acting on the block and directed to the left called? tension normal force weight friction

tension

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. What is the force acting on the block and directed to the right called? tension normal force weight friction

the surface of the table

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. Which object exerts a force on the block that is directed toward the left? the block itself the earth the surface of the table the string

the string

A string is attached to a heavy block. The string is used to pull the block to the right along a rough horizontal table. Which object exerts a force on the block that is directed toward the right? the block itself the earth the surface of the table the string

equal in magnitude but antiparallel to the force on the earth due to the moon.

According to Newton's 3rd law, the force on the (smaller) moon due to the (larger) earth is greater in magnitude and antiparallel to the force on the earth due to the moon. greater in magnitude and parallel to the force on the earth due to the moon. equal in magnitude but antiparallel to the force on the earth due to the moon. equal in magnitude and parallel to the force on the earth due to the moon. smaller in magnitude and antiparallel to the force on the earth due to the moon. smaller in magnitude and parallel to the force on the earth due to the moon.

The net force acting on it is zero.

An object cannot remain at rest unless which of the following holds? The net force acting on it is zero. The net force acting on it is constant and nonzero. There are no forces at all acting on it. There is only one force acting on it.

5N/ book

An upward force of magnitude _____ is exerted on the _____ by the table.

F1 on floor = Floor on F1 > F2 on 1 = F1 on 2 > F3 on 2 = F2 on 3 > F3 on 1 = F1 on 3

Assume the elevator is at rest. Rank the magnitude of the forces. F3 on 1, F1 on 3, F2 on 1, F1 on 2, F3 on 2, F2 on 3, F1 on floor, Floor on F1

the piano

Chadwick now needs to push the piano up a ramp and into a moving van. (Figure 2) The piano slides up the ramp without friction. Is Chadwick strong enough to push the piano up the ramp alone or must he get help? To solve this problem you should start by drawing a free-body diagram. Determine the object of interest for this situation.

A car is moving along a straight road at a constant speed. A hockey puck slides along a horizontal icy (frictionless) surface.

Consider the following situations: A car is moving along a straight road at a constant speed. A car is moving along a straight road while slowing down. A car is moving along a straight road while speeding up. A hockey puck slides along a horizontal icy (frictionless) surface. A hockey puck slides along a rough concrete surface. A cockroach is speeding up from rest. A rock is thrown horizontally; air resistance is negligible. A rock is thrown horizontally; air resistance is substantial. A rock is dropped vertically; air resistance is negligible. A rock is dropped vertically; air resistance is substantial. Which of these situations describe the motion shown in the motion diagram at point A?

A car is moving along a straight road while slowing down. A hockey puck slides along a rough concrete surface.

Consider the following situations: A car is moving along a straight road at a constant speed. A car is moving along a straight road while slowing down. A car is moving along a straight road while speeding up. A hockey puck slides along a horizontal icy (frictionless) surface. A hockey puck slides along a rough concrete surface. A cockroach is speeding up from rest. A rock is thrown horizontally; air resistance is negligible. A rock is thrown horizontally; air resistance is substantial. A rock is dropped vertically; air resistance is negligible. A rock is dropped vertically; air resistance is substantial. Which of these situations describe the motion shown in the motion diagram at point B?

A rock is thrown horizontally; air resistance is negligible.

Consider the following situations: A car is moving along a straight road at a constant speed. A car is moving along a straight road while slowing down. A car is moving along a straight road while speeding up. A hockey puck slides along a horizontal icy (frictionless) surface. A hockey puck slides along a rough concrete surface. A cockroach is speeding up from rest. A rock is thrown horizontally; air resistance is negligible. A rock is thrown horizontally; air resistance is substantial. A rock is dropped vertically; air resistance is negligible. A rock is dropped vertically; air resistance is substantial. Which of these situations describe the motion shown in the motion diagram at point C?

no

Do the downward force in Part A (gravity) and the upward force in Part B (upward force of magnitude 5N exerted on the book on the table) constitute a 3rd law pair?

true

Every force has one and only one 3rd law pair force. true false

a long-range force

First, consider a book resting on a horizontal table. The downward force acting on the book is __________. a contact force a long-range force

the earth

First, consider a book resting on a horizontal table. Which object exerts a downward force on the book? the book itself the earth the surface of the table

the surface of the table

First, consider a book resting on a horizontal table. Which object exerts an upward force on the book? the book itself the earth the surface of the table

a contact force

First, consider a book resting on a horizontal table. The upward force acting on the book is __________. a contact force a long-range force

weight

First, consider a book resting on a horizontal table. What is the downward force acting on the book called? tension normal force weight friction

normal force

First, consider a book resting on a horizontal table. What is the upward force acting on the book called? tension normal force weight friction

T1 = (M1+M2)a+(M1+M2)g

For Parts C and D the blocks are now accelerating upward (due to the tension in the strings) with acceleration of magnitude a. Find T1, the tension in the upper rope.

T2 = M2a+M2g

For Parts C and D the blocks are now accelerating upward (due to the tension in the strings) with acceleration of magnitude a. Find T2, the tension in the lower rope.

False

Given that two bodies interact via some force, the accelerations of these two bodies have the same magnitude but opposite directions. (Assume no other forces act on either body.) true false

The net force applied to the block is zero.

If a block is moving to the left at a constant velocity, what can one conclude? There is exactly one force applied to the block. The net force applied to the block is directed to the left. The net force applied to the block is zero. There must be no forces at all applied to the block.

F1 on floor = Floor on F1 > F2 on 1 = F1 on 2 > F3 on 2 = F2 on 3 > F3 on 1 = F1 on 3

Now, assume the elevator is moving upward at increasing speed. Rank the magnitude of the forces. F3 on 1, F1 on 3, F2 on 1, F1 on 2, F3 on 2, F2 on 3, F1 on floor, Floor on F1

Concave parabola from 0 to t, all in the +y axis

Plot position versus time. (Figure 3)

Line is x=0

Plot velocity versus time. (Figure 1)

Straight Line starts from zero, and is increasing (has positive slop)

Plot velocity versus time. (Figure 2)

gravitational force acting on the piano (piano's weight) force of the floor on the piano (normal force) force of Chadwick on the piano

Suppose that you are asked to solve the following problem: Chadwick is pushing a piano across a level floor (see the figure). (Figure 1) The piano can slide across the floor without friction. If Chadwick applies a horizontal force to the piano, what is the piano's acceleration? To solve this problem you should start by drawing a free-body diagram Identify the forces acting on the object of interest. From the list below, select the forces that act on the piano. Check all that apply. acceleration of the piano gravitational force acting on the piano (piano's weight) speed of the piano gravitational force acting on Chadwick (Chadwick's weight) force of the floor on the piano (normal force) force of the piano on the floor force of Chadwick on the piano force of the piano pushing on Chadwick

the piano

Suppose that you are asked to solve the following problem: Chadwick is pushing a piano across a level floor (see the figure). (Figure 1) The piano can slide across the floor without friction. If Chadwick applies a horizontal force to the piano, what is the piano's acceleration? To solve this problem you should start by drawing a free-body diagram. Determine the object of interest for the situation described in the problem introduction.

5 N / table / book / downward

The reaction to the force in Part B (upward force of magnitude 5N exerted on the book on the table) is a force of magnitude _____, exerted on the _____ by the _____. Its direction is _____.

friction

The same block is placed on the same rough table. However, this time, the string is disconnected and the block is given a quick push to the right. The block slides to the right and eventually stops. The following questions refer to the motion of the block after it is pushed but before it stops. What is the force acting on the block that is directed to the left called? tension normal force weight friction

1

The same block is placed on the same rough table. However, this time, the string is disconnected and the block is given a quick push to the right. The block slides to the right and eventually stops. The following questions refer to the motion of the block after it is pushed but before it stops. How many forces are acting on the block in the horizontal direction? 0 1 2 3

true

The two forces in each pair act in opposite directions. true false

false

The two forces in each pair can either both act on the same body or they can act on different bodies. true false

false

The two forces in each pair may have different physical origins (for instance, one of the forces could be due to gravity, and its pair force could be due to friction or electric charge). true false

true

The two forces of a 3rd law pair always act on different bodies. true false

cannot have a magnitude equal to 5N

Two forces, of magnitude 4N and 10N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________. Check all that apply. cannot have a magnitude equal to 5N cannot have a magnitude equal to 10N cannot have the same direction as the force with magnitude 10N must have a magnitude greater than 10N

The net force is zero.

What is the direction of the net force acting on the object at position A? upward downward to the left to the right The net force is zero.

to the left

What is the direction of the net force acting on the object at position B? upward downward to the left to the right The net force is zero.

downward

What is the direction of the net force acting on the object at position C? upward downward to the left to the right The net force is zero.

Newton's 1st law Newton's 2nd law

Which of Newton's laws could we have used to predict that the forces in Parts A (gravity) and B (upward force of magnitude 5N exerted on the book on the table) are equal and opposite? Check all that apply. Newton's 1st law Newton's 2nd law Newton's 3rd law

Newton's 3rd law

Which of Newton's laws could we have used to predict that the forces in Parts B (upward force of magnitude 5N exerted on the book on the table) and E (force of magnitude 5N exerted on the table by the book downward) are equal and opposite? Check all that apply. Newton's 1st law Newton's 2nd law Newton's 3rd law

1,2,3,4,5

Which of these diagrams correspond to a situation where the moving object (not necessarily the one shown in the motion diagram) is changing its velocity?

6

Which of these diagrams may possibly correspond to the situation at point A on the motion diagram?

3,5

Which of these diagrams may possibly correspond to the situation at point B on the motion diagram?

2,4

Which of these diagrams may possibly correspond to the situation at point C on the motion diagram?

T1 = (M1+M2)g

assume the blocks are at rest. Find T1, the tension in the upper rope.

T2 = M2g

assume the blocks are at rest. Find T2, the tension in the lower rope.