Chapter11GeneralRotation(2)

Chapter10~11Test

1、单选题:
​Consider an object on a rotating disk a distance r from its center, held in place on the disk by static friction. Which of the following statements is NOT true concerning this object? ​
选项:
A: If the angular speed is constant, the object has a zero acceleration. 
B: The object has a tangential acceleration only if the disk has an angular acceleration.
C: The object always has a centripetal acceleration except when the angular speed is zero.
D: If the angular speed is constant, the speed of object is also constant.
答案: 【 If the angular speed is constant, the object has a zero acceleration. 

2、单选题:

‌Consider the orbital motion of a planet going around the Sun. Which of the following statements about the motion is true?

‌选项:
A: Only the mechanical energy of planet is conserved.
B: Only the angular momentum of planet is conserved.
C: Both the angular momentum and mechanical energy of planet are conserved.
D: Neithor of the angular momentum or mechanical energy of planet is conserved.
答案: 【 Both the angular momentum and mechanical energy of planet are conserved.

3、单选题:

A bullet hits into a hanged uniform rod, the total momentum and total angular momentum of the system are both conserved after collision. Where does the bullet hit?

‍选项:
A: r = l /3
B: r = l /2
C: r = 2l /3
D: r = 3l /4
答案: 【 r = 2l /3

4、单选题:

Consider 3 objects with the same mass m but different shapes (solid cylinder, solid sphere and cylindrical shell). They all roll down from rest on an incline without slipping, which one rolls fastest?

‍选项:
A: The solid cylinder.
B: The solid sphere.
C: The cylindrical shell.
D: They roll equally fast.
答案: 【 The solid sphere.

5、判断题:
​When you watch a clock hanging on a vertical wall, the direction of angular velocity of the second hand is perpendicular to the wall and pointing outside. ‍
选项:
A: 正确
B: 错误
答案: 【 错误

6、判断题:
‍If we measure the rotational inertia of an object about different axes, we may obtain different values.‏
选项:
A: 正确
B: 错误
答案: 【 正确

7、判断题:
‏The angular momentum of a particle remains constant if there is no net torque acting on it.‍
选项:
A: 正确
B: 错误
答案: 【 正确

8、判断题:
‎Centrifugal force can be measured in noninertial frames, but it is not a real force, there is no object applying this force.​
选项:
A: 正确
B: 错误
答案: 【 正确

9、填空题:

‍Calculate the magnitude of net torque on the rod in Figure about the axis through O perpendicular to the page.

‌答案: 【 [41,42]

10、填空题:

A box is hanging on a pulley by massless rope, then the system starts to move without slip, How much is the acceleration of m

‌答案: 【 [6.5,6.7]

11、填空题:

How much is the rotational inertia I of a uniform thin disk (mass m, radius R), if the axis is along the line of its diameter?

‍答案: 【 0.25

12、填空题:

‌答案: 【 4

Chapter14Sound

Chapter12~14Test

1、单选题:
‏An object of mass 0.50 kg, hanging from a spring with a spring constant of 8.0 N/m, is set into a simple harmonic motion. What is the maximum speed of the object if its maximum displacement is 0.10 m? ‎
选项:
A: 0.20m/s
B: 0.40m/s
C: 0.80m/s
D: 1.60m/s
答案: 【 0.40m/s

2、单选题:

‍选项:
A: 0.5f
B: 0.707f
C: 1.414f
D: 2f
答案: 【 1.414f

3、单选题:
‌Which of the following statements is NOT necessarily true regarding mechanical waves?‏
选项:
A: They are sinusoidal in nature.
B: They carry energy.
C: They require a medium through which to propagate.
D: The wave speed depends on the properties of the medium in which they travel.
答案: 【 They are sinusoidal in nature.

4、单选题:

‍Someone is adjusting a guitar. He changes the length of guitar string from L to 0.9L, and the tension in the guitar string from T to 1.1T. After the adjustment, the frequency of guitar will change from f to ______.

‏选项:
A: 0.94f
B: 0.99f
C: 1.17f
D: 1.22f
答案: 【 1.17f

5、单选题:

‎选项:
A:
B:
C:
D:
答案: 【 

6、判断题:
A uniform circular motion on xoy plane can be treated as the superposition of a simple harmonic motion in x direction and another simple harmonic motion in y direction.​
选项:
A: 正确
B: 错误
答案: 【 正确

7、判断题:
‍In a damped harmonic motion, the vibrational energy keeps decreasing over time.‍
选项:
A: 正确
B: 错误
答案: 【 正确

8、判断题:
‍When a wave travels in medium, the particles in medium will oscillate with the same frequency, same amplitude and same phase.​
选项:
A: 正确
B: 错误
答案: 【 错误

9、判断题:
‏Consider an interference between two waves. At a certain position if the vibrations caused by two waves are in phase, they make a destructive interference.‏
选项:
A: 正确
B: 错误
答案: 【 错误

10、判断题:
​When we speak, the sound wave can be treated as a spherical wave. The sound level is measured lower for a longer distance to the speaker, because the intensity of sound wave decreases over distance.​
选项:
A: 正确
B: 错误
答案: 【 正确

11、填空题:

‌答案: 【 [0.14,0.142]

12、填空题:

‍答案: 【 [0.39,0

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