Is acceleration force

1. Gravitation is about equal to gravity, so GMM / R ^ 2 = mg, so
G = GM / R ^ 2

2. In the actual operation, it is not necessary to use the plus and minus sign, just specify the positive direction before solving the problem. In the positive direction, it will increase in the same direction, otherwise it will decrease.

3. Set the inclination angle as α
normal pressure of object to inclined plane = mgcos α
(without drawing, you can also imagine a special position: α= 0, positive pressure = mg, α= 90º Positive pressure = 0, so it's cos α， And sliding force = mgsin α On the contrary)
sliding friction f = n· μ= mgcos α·μ， The direction of force is opposite to that of motion.

4. Bearing vibration acceleration is an important index to measure the level of bearing manufacturing. It can be measured quantitatively with special instruments. Due to the imperfect manufacturing of bearings, all bearings will have a certain measurement value. Usually people hope that the smaller the vibration acceleration value of the bearing, the better, especially for the equipment requiring low noise and long life. According to the bearing diameter, different vibration acceleration levels will be specified. It can be represented by Z1, Z2, Z3, Z4, etc. The vibration acceleration level of Z1 is higher than that of Z2, and so on. For example: ordinary bearing is required to reach Z1 level, and Z4 level will be called "silent bearing". If the vibration acceleration level exceeds the standard requirements, there is a problem with the bearing. The internal causes are: the roundness, waviness and roughness of the steel ball or raceway are unqualified, the cleanliness is poor, the lubrication is poor, and so on. The external causes are: improper installation, pollution, poor supplementary lubrication, load bias or overload, frame resonance, and so on.

5. This is a problem of impulse. Let the momentum before and after a person touches an object change to M & # 8710; 5. In the process of collision, when the force of the object on the human is n and the collision time is t, there is M & # 8710; V=(N-Mg)t!

this n is equal to the human pressure on the object in the collision process. Because t is very small, this n is generally very large, far greater than gravity. The problem can be simplified as:
M & # 8710; V / T = n, this # 8710; V / T is the average acceleration of people in the collision process

I don't know if I'm wrong!

6. Generally speaking, it's human, but it's not human that works, it's machine

7. Using the formula, gravity is approximately equal to gravity
GMM / R ^ 2 = mg, GM = GR ^ 2
m = density × Volume = density × 4 / 3 * pi * R ^ 3
so G is proportional to R, so the acceleration of gravity is g / 2

8. You didn't even say the state of ab

9. First of all, we should distinguish between instantaneous acceleration and average acceleration. In high school, when the time difference is small enough, the average acceleration can be equal to the instantaneous acceleration; On the one hand, instantaneous acceleration is the limit of average acceleration; on the other hand, instantaneous acceleration is the first derivative of velocity. The instantaneous acceleration can be calculated along the tangent direction of V-T diagram according to the trajectory equation with the knowledge of calculus; The average velocity must depend on the displacement, which is defined as the difference between velocity and time
let's explain your example: for example, if a person walks from a to s, and then from s to Q, a, s, q are not in the same straight line, if we calculate his acceleration, is it the total distance from a to s, and then from s to Q, or the displacement from a to q? Whether it's the acceleration from a to s or the acceleration from s to Q, a to Q, the average acceleration is calculated by dividing the velocity difference by the time difference. When the end velocity direction is not on the same line, the triangle rule is used to calculate the velocity difference. The instantaneous acceleration follows the motion law of each segment, which is the original acceleration in as and the original acceleration in sq. In particular, it is not easy to get the acceleration mutation at the q-point directly, because the acceleration at the point is actually the instantaneous acceleration, and the acceleration at the turning point needs the knowledge of calculus, which will not be repeated here.

10. In a broad sense, acceleration equals force divided by mass, and acceleration of gravity equals gravity divided by mass. That's right
on the surface of the earth, it can be considered that the acceleration of gravity is equal to the constant of gravity.