**Excursions in Physics
**

First Hour Exam

February 5, 2003

Enter all your answers in the "scantron sheet" or the "bubble sheet". Turn in only that sheet. Anything you write on this exam will not be seen or used or considered or graded. Be sure your name is on the "bubble sheet" you hand in. Be sure your name is bubbled-in. Be sure your answers are recorded correctly.

Please come to class Friday. I will have a memo for each of you showing what I have recorded for your online quizzes. That may or may not agree with WebCT. What I have recorded is all that really counts. Let me know if my own gradebook needs to be changed.

For every question, also consider the following as a possible answer:

**e) none of the above**

Possibly useful information:

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For every question, also consider the following as a possible answer:

**e) none of the above**

1. What is the nature of Nature? In the absence of a net froce from the outside, an object

a) will fall to the ground.

b) always comes to rest.

**c) will continue to do what it is doing.**

d) pushes back on nearby objects.

2. In the absence of a net force from the outside, an object in motion

a) slowly comes to rest.

b) falls to the ground wit constant acceleration.

3. Kinematics is a description of motion. Motion was first well understood

a) by Aristotle and the ancient Greeks

b) by Ptolemy in Egypt

4. To measure the time needed to investigate motion,

a) Aristotle used a sundial

b) Ptolemy used the pendulum clock which had just been invented

5. Galileo was given a lifetime pension by the “city fathers” of Venice because he introduced

a) the pendulum clock.

b) the water clock.

6. Galileo entered the University and first planned to study

a) theology

d) geography

7. Galileo took a position as a professor of mathematics and taught

c) von Liebnetz’ integral calculus

d) Rubick’s cubism

8. Velocity is the time rate of change of

a) acceleration

b) speed

9. To calculate the average speed of an object, we need to know

a) force and mass.

d) force and time.

10. Acceleration is the time rate of change of

c) distance

d) momentum

11. Acceleration might be described as telling

a) where an object is located relative to an origin or reference point. (No, that’s

b) how fast something is moving. (No, that’s

12. What is the average speed of a motorcycle that travels 100 m in 20 s?

a) 20 m/s

b) 10 m/s

v = 100 m/20 s

v = 5 m/s

13. What is the average speed of a car that travels 125 km in 5 h?

a) 625 km/h

v = 125 km / 5 h

v = 25 km / h

d) 9.8 km/h

14. Consider a train that has an acceleration of 3 m/s^{2}. Initially,
at time t = 0, it has a velocity of v_{i }= 20 m/s. What
is its speed at t = 3 s?

a) 57 m/s

b) 41 m/s

**c) 29 m/s
v = v _{i} + a t
v = 20 m/s + (3 m/s^{2})(3 s)
v = 20 m/s + 9 m/s
v = 29 m/s
**d) 9 m/s

15. Consider a car that starts at rest and accelerates at 2 m/s

At that time, t = 4 s, how

a) 16 m/s

b) 12 m/s

v = v

v = 0 + (2 m/s

v = 0 + 8 m/s

v = 8 m/s

16. Consider a car that starts at rest and accelerates at 2 m/s

At that time,, t = 4 s, how

a) 32 m

b) 24 m

x = x

x = 0 + 0 + (

x = 16 m

d) 8 m

17. Consider a ball that is thrown upward at the edge of a canyon with an initial velocity of 30 m/s. Four seconds later, what is its

a) 40 m/s

b) 20 m/s

v = v

v = 30 m/s + ( - 10 m/s

v = 30 m/s - 40 m/s

v = - 10 m/s

d) – 30 m/s

18. Consider a ball that is thrown straight upward at the edge of a canyon with an initial velocity of 30 m/s. Four seconds later,

y = y

y = 0 + (30 m/s)(4 s) + (

y = 0 + 120 m - 80 m

y = 40 m

b) 20 m

c) – 10 m

d) – 30 m

19. A stone is dropped (from rest) from a bridge, high above a river. The stone takes five seconds before it hits the river. How fast is it going when it hits the water?

a) 5 m/s

b) 10 m/s

**c) 50 m/s
v = v _{i} + a t
v = 0 + ( - 10 m/s^{2})
v = - 50 m/s
The minus sign means it is going down.**

d) 100 m/s

20. Newton's First Law of Motion states that, in the absence of a net force, an object in motion will

a) eventually come to rest

b) continue in motion but slow down until it stops

21. Newton's Second Law of Motion explains the cause of motion and may be stated as

a) "All motion is relative."

b) "All objects fall with the same velocity."

a = F/m

That can then be turned around to our more familar form of

F = ma

22. Newton's Second Law of Motion explains the cause of motion and may be stated as

a) The net force on an object is inversely proportional to its weight.

b) The net force on an object produces an acceleration that is proportional to the time of action of that force.

That is F = ma directly.

d) The net force on an object is inversely proportional to the mass of the object.

23. Mass is a measure of

a) the volume of an object

b) the size of an object

24. The weight of an object is

a) the same thing as the mass of an object

b) the sum of all the forces on an object

25. The net force on a 1-kg object,

a) 9.8 N

b) 4.9 N

c) 1.00 N

The net force on any object

26. The net force on a 1-kg object,

In free fall, the

w = mg

w = (1.0 kg)(9.8 m/s

w = 9.8 N

b) 4.9 N

c) 1.00 N

d) zero

27. Harry the Painter has a weight of 500 N. When he is suspended as shown in the sketch here, what is the tension in the rope?

a) 1000 N

b) 500 N

**c) 250 N
Both ends of the rope are attached to Harry’s bo’sun’s chair. Each end
of the rope exerts a force up on Harry. Each end of the rope exerts a
force equal to the tension in the rope. Harry’s weight is 500 N so each
end of the rope pulls up with half his weight, 250 N.**

d) 25 N

28. A force of 24 N acts on an object whose mass is 8 kg.

This causes the object to accelerate at

a) 2 m/s

F = ma

24 N = (8 kg)( a )

24 N = (8 kg)(3 m/s

a = 3 m/s

c) 6 m/s

d) 12 m/s2

29. A car, with mass of 1,000 kg, accelerates at 2 m/s

The net force exerted on the car must be

a) 500 N

b) 1,000 N

F = ma

F = (1000 kg)(2 m/s

F= 2000 N

d) 10,000 N

30. The weight of a 1,000-kg car is

a) 500 N

b) 1,000 N

c) 2,000 N

w = mg

w = (1000 kg)(10 m/s

w = 10,000 N

31. A fireman, whose

a) 90 N

b) 150 N

We will need to use F = ma so we need to start by finding the fireman’s

w = m g

500 N = ( m )(10 m/s

500 N = ( 50 kg ) (10 m/s

m = 50 kg

F

F

F

F

F

F

500 N - ( 350 N ) = 150 N

F

d) 500 N

32. If a sailor drops a wrench from the top of a tall mast on a moving ship, it will fall and hit the deck

a) in front of the base of the.

**b) at the base of the mast.
**c) behind the base of the mast.

33. Sir Isaac Newton

a) first discovered the Law of Falling Bodies while at the University of Pisa.

b) was a close friend of Liebnitz and encouraged his early development of calculus.

34. Galileo

a) may be called the Father of Modern Optics.

b) wrote his findings in Polish while at the University of Paduah.

35. The hallmark of Modern Science is that

a) theories are accepted or rejected based upon the background or reputation of the scientists who propose them (horrors!)

d) predictions of theories must not contradict established authorities (such as Plato or Pythagores)

36. When applying Newton's Second Law of Motion, F = ma,

a) F is always the largest force present.

d) m must be the smallest mass in the system.

37. When using Newton's Third Law of Motion,

a) always cancel so this applies only to systems in equilibrium.

d) are always perpendicular to each other.

38. What value will the spring scale read in the system shown above? Little Nellie Newton weighs 50 N.

a) zero

**b) 25 N
This is similar to the question about Harry the Painter. Nellie’s weight of 50 N
pulls **

c) 50 N

d) 100 N

39. What is the net force on a 2-kg laboratory cart which accelerates at 3 m/s

a) 2 N

b) 3 N

F = ma

F = (2 kg)(3 m/s

F = 6 N

d) 12 N

40. Consider a 2-kg lab cart which has an initial velocity of 5 m/s and then accelerates at 3 m/s^{2} for four seconds. At that time, t = 4 s, how **fast** is it moving?

a) 20 m/s

**b) 17 m/s
v = v _{i} + a t
v = 5 m/s + (3 m/s^{2})(4 s)
v = 5 m/s + 12 m/s
v = 17 m/s**

c) 12 m/s

d) 8 m/s

41. Consider a 2-kg lab cart which has an initial velocity of 5 m/s and then accelerates at 3 m/s

a) 48 m

x = x

x = 0 + (5 m/s)(4 s) + (

x = 0 + 20 m/s + 24 m/s

x = 44 m/s

c) 32 m

d) 24 m

42. In the absence of air resistance,

a) heavier objects fall with a greater acceleration than lighter objects.

43. A roller coaster is launched from rest to 28 m/s (that’s about 100 km/h or 60 mi/h) in 3.5 seconds. That is an acceleration of

a) 2 m/s^{2}

b) 4 m/s^{2}

**c) 8 m/s ^{2}
a = change in velocity / change in time
a = (28 m/s)/(3.5 s)
a = 8 m/s^{2} **

d) 12 m/s

44. A particular roller coaster is launched with an acceleration of 5 m/s^{2}. What is the net force required to launch a 1,000-kg car?

a) 200 N

b) 1,000 N

**c) 5,000 N
F = m a
F = (1000 kg)(5 m/s**

d) 10,000 N

45. A force of 12 N is applied to a laboratory cart and an acceleration of 3 m/s

a) 2 kg

F = m a

12 N = ( m ) (3 m/s

12 N = ( 4 kg ) (3 m/s

m = 4 kg

c) 8 kg

d) 36 kg

46. When any object moves in a circle

a) its speed must decrease

c) its velocity is directed toward the center of the circle

47. The net force on any object which moves in a circle

a) causes the speed to increase.

b) is directed along a line tangent to the circle.

c) increases as the object slows down.

48. Newton’s Third Law of Motion explains how two objects interact and may be stated as

a) "All motion is relative."

b) "All objects fall with the same velocity."

49. The hallmark of Modern Science is that

a) theories are accepted or rejected based upon the background or reputation of the scientists who propose them.

d) predictions of theories must not contradict established authorities (such as Plato or Pythagores).

50. The four fundamental forces are

a) friction, weight, centripetal, inertial

b) friction, air resistance, centrifugal, weight