Name: 
 

Physics 12 - Chapter 2 Quiz


True/False
Indicate whether the sentence or statement is true or false.
 

1. 
When a ball is rising upward after you toss it vertically, the net force on the ball is equal to the force of gravity on the ball.
 

2. 
You pull horizontally on a rope, attached firmly to a hook on the wall, with a force of magnitude 16 N. If you pull horizontally with a force of the same magnitude on a string held firmly by a friend, the magnitude of the tension in the string is 32 N.
 

3. 
A grocery cart, at rest on a level floor, experiences a normal force of magnitude 155 N. You push on the cart handle with a force directed at an angle of 25° below the horizontal. The magnitude of the normal force is now less than 155 N.
 

4. 
Snow conditions are identical throughout the ski valley in Figure 1. The coefficient of kinetic friction between a skier’s skis and the snow is 0.18 when the skier is travelling down the one side of the valley. As the skier moves up the other side of the valley, the coefficient of kinetic friction exceeds 0.18 because gravity is acting against the skier’s motion.

p12ch2_files/i0050000.jpg
Figure 1
 

5. 
It is impossible for an object to be travelling eastward while experiencing a westward net force.
 

6. 
It is possible for the sum of three vector forces of equal magnitude to be zero.
 

7. 
Static friction is always greater than kinetic friction.
 

8. 
One possible SI unit of weight is the kilogram.
 

9. 
When you are standing at rest on the floor, there are two action-reaction pairs of forces involved.
 

10. 
Viscosity and air resistance are both types of friction involving fluids.
 

11. 
Fictitious forces must be invented to explain observations whenever the chosen frame of reference is in motion.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

12. 
A person of mass 65 kg is ascending on an escalator at a constant velocity of 2.5 m/s [22° above the horizontal]. The magnitude of the net force acting on the person is
a.
0 N
b.
6.4 p12ch2_files/i0140000.jpg 102 N
c.
5.9 p12ch2_files/i0140001.jpg 102 N
d.
2.4 p12ch2_files/i0140002.jpg 102 N
e.
1.6 p12ch2_files/i0140003.jpg 102 N
 

13. 
On a windy day, a quarterback throws a football into the wind. After the football has left the quarterback’s hand and is moving through the air, the correct list of the force(s) acting on the football is
a.
a force from the throw and the downward force of gravity
b.
a force from the throw, a force exerted by the air, and the downward force of gravity
c.
a force exerted by the air and a force from the throw
d.
a force exerted by the air and the downward force of gravity
e.
the downward force of gravity
 

14. 
A skier of mass m is sliding down a snowy slope that is inclined at an angle p12ch2_files/i0160000.jpg above the horizontal. The magnitude of the normal force on the skier is
a.
mg tan p12ch2_files/i0160001.jpg
b.
mg cos p12ch2_files/i0160002.jpg
c.
mg sin p12ch2_files/i0160003.jpg
d.
mg
e.
zero
 

15. 
A soft-drink can is resting on a table. If Earth’s force of gravity on the can is the action force, the reaction force is
a.
an upward normal force exerted by the table on the can
b.
a downward gravitational force exerted by Earth on the table
c.
a downward normal force exerted on the table by the can
d.
an upward force of gravity on Earth by the can
e.
none of these
 

16. 
The coefficients of friction between a box of mass 9.5 kg and the horizontal floor beneath it are
mS = 0.65 and mK = 0.49. The box is stationary. The magnitude of the minimum horizontal force that would suffice to set the box into motion is
a.
93 N
b.
61 N
c.
46 N
d.
6.2 N
e.
4.7 N
 
 
For questions 17 to 21, refer to Figure 2.
p12ch2_files/i0190000.jpg
Figure 2
Two dynamics carts, one a single cart of mass 1.0 kg, the other a double cart of mass 2.0 kg, each with essentially frictionless wheels, are in contact and at rest. The compression spring on the single cart is suddenly released, causing the cart to exert an average force of 2.0 N [E] on the double cart for 0.50 s.
 

17. 
During the time interval that the spring acts on the double cart, the force exerted by the double cart on the single cart is
a.
2.0 N [W]
b.
0.0 N
c.
2.0 N [E]
d.
4.0 N [W]
e.
4.0 N [E]
 

18. 
During the spring interaction, the net force acting on the single cart is
a.
4.0 N [W]
b.
2.0 N [W]
c.
2.0 N [E]
d.
4.0 N [W]
e.
zero
 

19. 
During the interaction, the acceleration of the double cart is
a.
0.33 m/s2 [E]
b.
1.0 m/s2 [E]
c.
3.0 m/s2 [E]
d.
0.50 m/s2 [E]
e.
2.0 m/s2 [E]
 

20. 
The velocity of the double cart exactly 0.20 s after the compression spring is released is
a.
0.25 m/s [E]
b.
1.0 m/s [E]
c.
4.0 m/s [E]
d.
zero
e.
less than 0.25 m/s [E], but greater than zero
 

21. 
After the spring interaction is complete and the carts are separated, the net force acting on the single cart is
a.
19.6 N [down]
b.
2.0 N [W]
c.
19.6 N [up]
d.
the vector sum of 19.6 N [down] and 2.0 N [W]
e.
zero
 



 
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