As shown in the figure, a circle around the center line AB rotates at a certain angular speed, P and Q are two points on the ring, and their positions are shown in the figure A. The angular velocity of P and Q is the same, the linear velocity of B. P and Q is the same, the ratio of angular velocity of C. P and Q is 3:1d, and the ratio of linear velocity of P and Q is 3:1

As shown in the figure, a circle around the center line AB rotates at a certain angular speed, P and Q are two points on the ring, and their positions are shown in the figure A. The angular velocity of P and Q is the same, the linear velocity of B. P and Q is the same, the ratio of angular velocity of C. P and Q is 3:1d, and the ratio of linear velocity of P and Q is 3:1

A. So a is correct and B is wrong. The radius ratio of B, P and Q is rsin60: rsin30 = 3:1. According to v = R ω, the linear velocity ratio of P and Q is 3:1. So B is wrong and D is correct

Proof that the angular velocity of contact point between pure rolling and ground is the same as that of surface

If the coordinate system is set up on the center of the circle, then it turns into uniform rotation. The linear velocity of each point is the same, and the angular velocity is also the same;
Empirically, we use the base point method to select the center of the circle as the base point. The angular velocity of each point on the circle is the same, which is actually the same as the above method

How to calculate?
Helicopter wings rotate at an angular velocity of 320 rev / min per minute. What is the unit of angular velocity in radians?
To write down the process of calculation,

320rev / min = (16 / 3) rev / S = 2 * (16 / 3) rad / S = 2 * 3.14 * (16 / 3) rad / S = 33.5rad/s
Rad --- radian

The difference between the velocity of particle vibration and the velocity of wave propagation
What is the difference between the velocity of particle vibration and that of wave propagation

The particle vibrates harmonically in situ and does not move with the wave. The velocity v = A / w * cos (WT)
The wave propagation velocity is actually the propagation velocity of the same phase point, which can be understood as the moving velocity of the particles reaching the maximum displacement one after another. This velocity is usually uniform and related to the medium

A simple harmonic ground wave source vibrates 10 times per second, and the wave propagation velocity in a medium is 10 m / s

If a harmonic wave source vibrates 10 times per second, the frequency is f = 10 (/ s)
Period T = 1 / F = 0.1 (s)
Wavelength = t * V = 0.1 * 10 = 1 (m)

Maximum lateral vibration velocity
What does it mean? Vmax = w * a?

When S-wave propagates, the vibration direction of the particle is closely related to the wave propagation

There is a simple harmonic motion of an object with an amplitude of 4cm and a frequency of 3Hz. How many distances has the object passed in 2S

If the amplitude is 4cm, the total vibration distance is 16cm, the frequency is 3Hz, and the total vibration times per second is 3, so the distance per second is 16x3 = 48CM, and the distance in 2 seconds is 96cm

A particle makes a simple harmonic motion near the equilibrium position o point. After passing o point at a certain time, it passes through M point for the first time in 3 seconds, and then passes through M point for the second time in 2 seconds___ S or___ If the distance of the particle starting from point O is 20cm in 20s, the vibration amplitude of the particle is___ Cm or___ cm．

(1) According to the problem, if a particle moves from O to m, draw a diagram of its complete vibration process, as shown in Figure 1, then the period of particle vibration is t = 4 × (3 + 12 × 2) s = 16S, and the time needed for the oscillator to pass through M for the third time is t = t-2s = 14s

When a particle moves from O to one side, it passes through a point m for the first time after 3 s,
Then it moves forward, and after another 2 seconds, it passes through point m for the second time. How long does it take for the particle to pass through point m for the third time?

It can be divided into two cases: case 1: it takes 3 s for the particle to move from the equilibrium position to the m point, and it takes 2 s for the particle to reach the maximum displacement and return to the m point after passing through the m point. Then the period of the simple harmonic vibration of the particle is 4 * (3 + 2 / 2) = 16 S, and the time of the third passing through the m point should be the time of the first passing through the m point plus 16 s

As shown in the figure, the particle o starts to do simple harmonic vibration from the moment t = 0. In the figure, ox represents an elastic rope, OA = 14m, ab = BC = 10m. In the second second second, a vibrates twice more than B, and B vibrates five times more than C. It is known that the final wave has passed through point C in the second second second, then the frequency of the particle vibration is______ Hz, the wave velocity on the rope is______ m/s．

First of all, suppose that the wave velocity is V and the period is t. according to the title, C has passed by the end of the second second, which means that it has not just arrived at C at the end of the second. So suppose that y has arrived at the end of the second, then x has arrived at the end of the first second