Conceptual Physics Chapter 5 Test and KEY

 

16.             Note the free body diagrams below. Which FBD shows an object accelerating?

 

a.

c.

b.

d.

 

 

                  17. An apple, such as the one pictured below, weighs one Newton. When this apple is held in your hand what is the net force on the apple?

a.

0 N

c.

1.0 N

b.

0.1 N

d.

9.8 N

 

 

                  18. The combination of all forces acting on an object is called

a.

the net force.

c.

the unbalanced force.

b.

the object force.

d.

the balanced force.

 

 

                  19. Note the two masses below. A 100 N force is applied to each mass. What is the relationship between the magnitude of the masses and the acceleration each will experience when the 100 N force is applied?

a.

The acceleration is unrelated to the mass.

c.

The acceleration is inversely related to the mass.

b.

The acceleration is directly proportional to the mass.

d.

 The acceleration is quadraticly related to the mass.

 

 

                  20. Note the figure below. What is the acceleration of the wagon?

a.

0 m/s2

c.

1.0 m/s2

b.

0.1 m/s2

d.

10  m/s2

 

 

                  21. An apple that weighs 1 N, such as the one pictured below, is in free fall. What is the net force on the apple?

a.

0.0 N

c.

1.0 N

b.

0.1 N

d.

9.8 N

 

 

                  22. An object with a constant mass has a constant non-zero force applied to it, as a result the object is

a.

moving at uniform velocity.

c.

not moving at all.

b.

moving at uniform acceleration.

d.

moving in an elliptical path

 

 

                  23. Which statement best describes the acceleration of an object falling at terminal velocity?

a.

Its inertia is increasing.

c.

Its velocity is constant and non-zero.

b.

Its acceleration is decreasing

d.

Its acceleration is constant and non-zero.

 

 

                  24. When a parachutist. such as the one pictured below, is approching terminal velocity, his velocity is ___ while his acceleration is ___.

a.

increasing, increasing

c.

increasing, decreasing

b.

decreasing, decreasing

d.

decreasing, increasing

 

 

                  25. Which of the items below describes a situation that would cause the greatest pressure to be exerted on the ground?

a.

A woman standing in running shoes.

c.

A woman standing in high heel shoes.

b.

A woman standing on skis

d.

A woman standing barefoot on the back of an elephant?

 

 

                  26. Note the figure below. The arrow is pointing at the very top of the ball’s trajectory. At this point what is the net force on this ball?

a.

Exactly zero Newtons.

c.

A force less than the weight of the ball.

b.

A force greater than the weight of the ball.

d.

A force equal to the weight of the ball.

 

 

                  27. Note the three objects in free fall pictured below. Although each of these objects have a different mass they all accelerate at the same rate in the absence of air resistance. This is because

a.

the force acting on them is the same.

c.

their weight to mass ratio, F/m. is the same.

b.

they all have the same inertia in free fall.

d.

their weight to inertia ratio depends on their acceleration.

 

 

                  28. Which of these correctly describes the SI unit for pressure?

a.

The product of force and acceleration.

c.

The ratio of force and area.

b.

The product of force and distance.

d.

the ration of force and mass.

 

 

                  29. Note the figure below. How does the acceleration of mass one compare to the acceleration of mass two?

a.

It is three times less.

c.

It is three times more.

b.

It is the same.

d.

It is nine times more.

 

 

                  30. A student could lay on the bed of nails without injury because

a.

there were so few nails that the chances of injury were small.

c.

no student weighed enough for the nails to cause injury

b.

the nails were first dulled to a nearly flat tip so that there was no possibility of a nail piercing anyone’s skin.

d.

there were so many nails that each one exerted less than a Newton of force on the skin.

 

 

True/False (6)

Indicate whether the statement is true or false. Mark your answer document ‘A’ for true and ‘B’ for false.

 

                  31. The combination of all forces acting on an object is called the object force.

 

                  32. A 100 N bag of bricks is falling a terminal speed, this means that there is a 100 N force of air resistance acting on the bag of bricks.

 

                  33. The pascal is the SI unit for pressure and it is calculated by dividing the force exerted on an object by the area over which the force is applied.

 

                  34. If you held an object that weighed an Newton in one hand and an object that weighed a pound in the other hand you could easily tell that the heavier object is the one that weighs a Newton.

 

                  35. The normal force always acts vertically, no matter the angle of the surface producing that normal force.

 

                  36. The force of gravity acts on a book lying on a desk, the desk produces a normal force that exactly equals the force of gravity.

 

Problems (4)

Solve the problems below using scratch paper as needed. The answers go the the reverse side of your answer document in the section  labeled “Griddable D”. Do not grid more than two decimal places, rounding the second decimal as necessary.

 

                  37. What is the force necessary to accelerate a 55 kg student 1.5 m/s2?

 

                  38. A force of 5250 N is required to accelerate a pick-up truck at 1.5 m/s2. What is the mass of the pick-up truck?

 

                  39. What is the acceleration of a 0.45 kg soccer ball as it rolls down a hill with a force of 2.43 N?

 

40.  Both feet of the average student covers an area of  0.006 m2; the weight of an average student is 500 N (110 lb). How much pressure is exerted by the average student standing on the floor?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

KEY:

           16  D                                              20  A                                   24 C                28  C

       17   A                           21  C                                              25 C               29  A

       18   A                           22  B                                              26 D              30  D

       19   C                           23  C                                              27  C

 

TRUE/FALSE

           31  F                                               33  T                                   35  F

        32  T                           34  F                                               36  T

 

 

 

 

31.  The combination of all forces acting on an object is called the net force.

34. If you held an object that weighed a Newton in one hand and an object that weighed a pound in the other hand, the object that weighed a pound would be observably heavier (because a Newton weighs one-fourth of a pound).

35. The normal force does not always act vertically; it is perpendicular to the surface of contact.

 

 

PROBLEM