Download Chapter Test A

Assessment
Chapter Test A
Teacher Notes and Answers
Forces and the Laws of Motion
CHAPTER TEST A (GENERAL)
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Forces exerted by the object do not change
its motion.
An object at rest remains at rest and an
object in motion continues in motion with
constant velocity unless it experiences a net
external force.
∑ F is the vector sum of the external forces
acting on the object.
In most cases, air resistance increases with
increasing speed.
27 N, to the right
Given
F1 = 102 N, to the right
24. 16 N
Given
m = 33 kg
a = 0.50 m/s2
Solution
Fnet, x = ∑ Fx = max =
(32 kg)(0.50 m/s2 ) = 16 N
25. 10.4 N
Given
m = 1.10 kg
α = 15.0°
g = 9.81 m/s2
Solution
Fnet, y = ∑ Fy = Fn − Fy = 0
θ = 180° − 90° − 15.0° = 75.0°
Fn = Fy = Fg sin θ = mg sin θ
Fn = (1.10 kg)(9.81 m/s2 )(sin 75.0°)
= 10.4 N
F2 = 75 N, to the left
Solution
Fnet = F1 + F2
Fnet = F1 − F2 = 102 N − 75 N = 27 N
Fnet = 27 N, to the right
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Physics
Chapter Test
Name: _____________________ Class:______________ Date: _______________
Assessment
Forces and the Laws of Motion
Chapter Test A
MULTIPLE CHOICE
In the space provided, write the letter of the term or phrase that best completes
each statement or best answers each question.
_____ 1. Which of the following is the cause of an acceleration?
a. speed
c. force
b. inertia
d. velocity
_____ 2. What causes a moving object to change direction?
a. acceleration
c. inertia
b. velocity
d. force
_____ 3. Which of the following forces exists between objects even in the
absence of direct physical contact?
a. frictional force
c. contact force
b. fundamental force
d. field force
_____ 4. A newton is equivalent to which of the following quantities?
a. kg
c. kg•m/s2
b. kg•m/s
d. kg•(m/s)2
_____ 5. The length of a force vector represents the
a. cause of the force.
b. direction of the force.
c. magnitude of the force.
d. type of force.
_____ 6. A free-body diagram represents all of the following except
a. the object.
b. forces as vectors.
c. forces exerted by the object.
d. forces exerted on the object.
_____ 7. In the free-body diagram shown to the right,
which of the following is the gravitational force
acting on the car?
a. 5800 N
c. 14 700 N
b. 775 N
d. 13 690 N
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Holt McDougal Physics
1
Chapter Test
Name: _____________________ Class:______________ Date: _______________
Chapter Test A continued
_____ 8. Which of the following is the tendency of an object to maintain its state
of motion?
a. acceleration
c. force
b. inertia
d. velocity
_____ 9. A crate is released on a frictionless plank inclined at angle θ with
respect to the horizontal. Which of the following relationships is true?
(Assume that the x-axis is parallel to the surface of the incline.)
a. Fy = Fg
c. Fy = Fx
b. Fx = 0
d. none of the above
_____ 10. A car goes forward along a level road at constant velocity. The
additional force needed to bring the car into equilibrium is
a. greater than the normal force times the coefficient of static friction.
b. equal to the normal force times the coefficient of static friction.
c. the normal force times the coefficient of kinetic friction.
d. zero.
_____ 11. If a nonzero net force is acting on an object, then the object is definitely
a. at rest.
c. being accelerated.
b. moving with a constant velocity. d. losing mass.
_____ 12. Which statement about the acceleration of an object is correct?
a. The acceleration of an object is directly proportional to the net
external force acting on the object and inversely proportional to the
mass of the object.
b. The acceleration of an object is directly proportional to the net
external force acting on the object and directly proportional to the
mass of the object.
c. The acceleration of an object is inversely proportional to the net
external force acting on the object and inversely proportional to the
mass of the object.
d. The acceleration of an object is inversely proportional to the net
external force acting on the object and directly proportional to the
mass of the object.
_____ 13. Which are simultaneous equal but opposite forces resulting from the
interaction of two objects?
a. net external forces
c. gravitational forces
b. field forces
d. action-reaction pairs
_____ 14. Newton’s third law of motion involves the interactions of
a. one object and one force.
c. two objects and one force.
b. one object and two forces.
d. two objects and two forces.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Physics
2
Chapter Test
Name: _____________________ Class:______________ Date: _______________
Chapter Test A continued
_____ 15. The magnitude of the gravitational force acting on an object is
a. frictional force.
c. inertia.
b. weight.
d. mass.
_____ 16. A measure of the quantity of matter is
a. density.
c. force.
b. weight.
d. mass.
_____ 17. A change in the gravitational force acting on an object will affect
the object’s
a. mass.
c. weight.
b. coefficient of static friction.
d. inertia.
_____ 18. What are the units of the coefficient of friction?
a. N
c. N2
b. 1/N
d. The coefficient of friction has
no units.
SHORT ANSWER
19. In a free-body diagram of an object, why are forces exerted by the object not
included in the diagram?
______________________________________________________
______________________________________________________
20. State Newton’s first law of motion.
______________________________________________________
______________________________________________________
______________________________________________________
21. In the equation form of Newton’s second law, ΣF = ma, what does ΣF
represent?
______________________________________________________
______________________________________________________
22. What happens to air resistance when an object accelerates?
______________________________________________________
______________________________________________________
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Holt McDougal Physics
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Chapter Test
Name: _____________________ Class:______________ Date: _______________
Chapter Test A continued
PROBLEM
23. In a game of tug-of-war, a rope is pulled by a force of 75 N to the left and by a
force of 102 N to the right. What is the magnitude and direction of the net
horizontal force on the rope?
24. A wagon having a mass of 32 kg is accelerated across a level road at
0.50 m/s2. What net force acts on the wagon horizontally?
25. Basking in the sun, a 1.10−kg lizard lies on a flat rock tilted at an angle of
15.0° with respect to the horizontal. What is the magnitude of the normal force
exerted by the rock on the lizard?
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Holt McDougal Physics
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Chapter Test