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起止时间:2020-12-09到2021-07-26
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02 Motion in Two or Three Dimensions Unit Test 1
1、 Which of the following is a vector quantity:
A:speed
B:time
C:acceleration
D:mass
答案: acceleration
2、 In right handed coordinate system which axis is considered to be positive?
A:The thumb is z-axis, fingers curled from y-axis to x-axis
B:The thumb is x-axis, fingers curled from z-axis to y-axis
C:The thumb is y-axis, fingers curled from x-axis to z-axis
D: The thumb is z-axis, fingers curled from x-axis to y-axis
答案: The thumb is z-axis, fingers curled from x-axis to y-axis
3、 What is the magnitude of the Cartesian vector having the x, y and z axis components to be A, B and C?
A:Square root of the squares each A, B and C
B: Square of the squares each A, B and C
C:Cube root of the squares each A, B and C
D:Cube of the squares each A, B and C
答案: Square root of the squares each A, B and C
4、 The radial component of velocity for a particle moving in a circular path is ______.
A:A non-zero constant
B: Radius itself
C:Variable
D:Zero
答案: Zero
5、 When acceleration is _, a velocity of a particle is constant.
A:Constant but non zero
B: Maximum
C: Zero
D:None of the above
答案: Zero
6、 A block sliding down an inclined plane has acceleration ___ acceleration due to gravity.
A: Less than
B:Greater than
C: Same as
D:None of these
答案: Less than
7、 A physics professor leaves her house and walks along the sidewalk toward campus. After 5 min it starts to rain and she returns home. Her distance from her house as a function of time is shown in Fig. At Point ___( fill in the labeled points I/ II/ III/ IV/ V) is her velocity zero. 
A:IV
B:I
C:V
D:II
答案: IV
8、 A physics professor leaves her house and walks along the sidewalk toward campus. After 5 min it starts to rain and she returns home. Her distance from her house as a function of time is shown in Fig. At Point ___( fill in the labeled points I/ II/ III/ IV/ V) is her velocity increasing in magnitude.
A:IV
B:I
C:V
D:II
答案: II
9、 A model of a helicopter rotor has four blades, each 3.40 m long from the central shaft to the blade tip. The model is rotated in a wind tunnel at 550 rev/min. The linear speed of the blade tip is __m/s.
A:19.6m/s
B:196m/s
C:208m/s
D: 20.8m/s
答案: 196m/s
10、 An astronaut has left the International Space Station to test a new space scooter. Her partner measures the following velocity changes, taking place in a 10s interval. At the beginning she is moving toward the right at 15.0 m/s, and at the end she is moving toward the left at 15.0 m/s. The magnitude of her average acceleration is__m/s^2.
A:3
B:8
C:12
D:7
答案: 3
11、 A body that’s moving with a constant speed travels once around a circular path. Which of the following is/are true concerning the motion?I. The displacement is zero. II. The average speed is zero. III. The acceleration is zero.
A:I only
B:I and II
C:I and III
D: II and III
E:II only
F:III only
答案: I only
12、 A rock is thrown off a 35 m cliff at a 45° angle above the horizontal. Which is the following is true regarding the acceleration of the rock?
A:The acceleration will be of magnitude g and have both horizontal and vertical components.
B:At the peak of the rock’s path, the magnitude of acceleration will be half of what it was when the rock was initially thrown.
C:The acceleration will be of magnitude g and in a downward direction.
D:The acceleration will be downward during the rock’s ascent and upward during the rock’s descent.
E:The acceleration will increase throughout the rock’s flight.
答案: The acceleration will be of magnitude g and in a downward direction.
13、 A small stone is thrown horizontally with an initial speed of 30 m/s from a bridge. Find the stone’s total speed when it enters the water 4 seconds later. (Ignore air resistance.)
A:30 m/s
B:40 m/s
C:50 m/s
D:60 m/s
E:70 m/s
F:80 m/s
答案: 50 m/s
14、 Which one of the following statements is true concerning the motion of an ideal projectile launched at an angle of 45°to the horizontal?
A:The acceleration vector points opposite to the velocity vector on the way up and in the same direction as the velocity vector on the way down.
B:The speed at the top of the trajectory is zero.
C:The object’s total speed remains constant during the entire flight.
D:The horizontal speed decreases on the way up and increases on the way down.
E:The vertical speed decreases on the way up and increases on the way down.
答案: The vertical speed decreases on the way up and increases on the way down.
15、 The position of an object moving in a straight line is given by the equation x = (3t3 + 7t + 5) m, where t is in seconds. What is the object’s acceleration at time t = 5 seconds?
A:415 m/s2
B:232 m/s2
C:115 m/s2
D: 90 m/s2
E:35 m/s2
答案: 90 m/s2
16、 The earth has a radius of 6380 km and turns around once on its axis in 24 h. What is the radial acceleration of an object at the earth’s equator? _ m/s2
A:0.034
B:0.0014
C:1.2
D:0.87
E:0.095
答案: 0.034
17、 The earth has a radius of 6380 km and turns around once on its axis in 24 h. If arad at the equator is greater than g, objects will fly off the earth’s surface and into space. What would the period of the earth’s rotation have to be for this to occur?
A:5070 S
B:8060 S
C:3.4 h
D:6080 S
E:4.6 h
F:1.4h
答案: 5070 S ;
1.4h
18、 A ball is projected with an initial velocity of magnitude v0 = 40 m/s toward a vertical wall as shown in the figure. How long does the ball take to reach the wall?______ S 
A:0.3
B:0.4
C:1.0
D:2.0
E:3.0
F:4.0
答案: 1.0
19、 Two projectiles are launched at 100 m/s, the angle of elevation for the first being 30° and for the second 60°. Which of the following statements is false?
A:Both projectiles have the same acceleration while in flight.
B:The second projectile has the lower speed at maximum altitude.
C:Both projectiles have the same range.
D:All of the other statements are false.
答案: All of the other statements are false.
20、 Plane A is flying at 400 mph in the northeast direction relative to the earth. Plane B is flying at 500 mph in the north direction relative to the earth. What is the speed of Plane B as observed from Plane A?
A:900 mph
B:640 mph
C:357 mph
D:100 mph
答案: 357 mph
05 Work and Kinetic Energy Unit Test 2
1、 Two monkeys of equal mass are holding onto a single vine of negligible mass that hangs vertically from a tree, with one monkey a few meters higher than the other. What is the ratio of the tension in the vine above the upper monkey to the tension in the vine between the two monkeys?
A:2
B:0.5
C:1.5
D:More information is required
答案: 2
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