Representation method 1 (time parameter formula):
x=vxt
y=-0.5gt2
v2=vx2+vy2= vx2+(vt)2
Gravity acceleration is the acceleration of an object under the action of gravity. Assuming that the distance between a particle with mass m and a uniform sphere with mass m is r, the gravity on the mass is:
Where g is the gravity constant. According to Newton's second law
The available acceleration of gravity is
Near the surface of the earth, the acceleration G of a particle's free fall is slightly different from its gravity acceleration A, and the weight mg of a particle is also different from its gravity, because the earth will rotate. If the earth's rotation is considered, then:
(measured weight mg)= (gravity ma)- (mass m× centripetal acceleration w? r)
You can get:
(acceleration of free fall g)= (acceleration of gravity a)- (centripetal acceleration w? r)
Note that the subtraction in the above formula is vector subtraction. In fact, the acceleration of a free-falling body has a small specific gravity and a slightly different direction, with the greatest difference at the equator, but the difference between them is only about 0.034m/s due to the relationship between the radius of the earth and the rotation period? Therefore, in the calculation of daily use, the difference between weight and gravity is usually negligible.
The acceleration of all objects falling near the surface is between 9.78 and 9.83 m/s? The difference depends on latitude and other factors (the equator is the least and the north and south poles are the largest), and the standard gravity acceleration is 9.80665 m/s? (For the convenience of calculation, generally use 9.8 1 m/s? Or 10 m/s? )。
Acceleration is a physical quantity and a vector in physics, which is mainly used in classical physics. Generally expressed in letters, the unit in the international system of units is meters per square second (). Acceleration is the rate of change of velocity vector relative to time, which describes the direction and magnitude of velocity.
Acceleration is caused by force and becomes a very important physical quantity in classical mechanics because of Newton's second law. The acceleration of a reference system in an inertial reference system is expressed as the inertial force in the reference system. Acceleration is also directly or indirectly related to various effects, such as electromagnetic radiation.
Simply put, speed describes how the position changes, and acceleration describes how the speed changes. For example, an object is thrown horizontally forward. At first, its speed went straight ahead, but due to the action of gravity, it began to fall while moving forward, that is, its speed changed. What changes the speed of objects here is mainly the acceleration of gravity caused by the gravity of the earth.
See also: Vector.
Acceleration has vector property, that is, it needs to be described by magnitude and direction. If an object moving forward on a smooth horizontal plane is forced to the left or right, that is, given different accelerations, its speed will change, but the left acceleration and the right acceleration obviously have different effects. Similarly, different forces lead to different accelerations and different final results. As a vector, the superposition and decomposition of acceleration follow parallelogram law and triangle law respectively.
More precisely, acceleration describes the rate of change of speed with time. It should be noted that the speed of an object with non-zero acceleration (called speed) does not necessarily change because the speed is also a vector. In fact, if the acceleration remains perpendicular to the speed, the speed will remain the same and the direction will never change. This kind of situation is the most common in life, such as the movement of small objects tied to the other end of the fixed line, and the movement of charged particles when they are only subjected to Lorentz force of static magnetic field.
[Edit] Average acceleration in linear motion Instantaneous acceleration makes particle A move on the number axis. Where is the time and where is it after the time, then define the instantaneous speed (referred to as speed) of particle A at that moment as
Among them, it refers to finding the first derivative of displacement with respect to time and finding the slope on the time-displacement diagram.
First, the average acceleration from time to time is defined as
The average acceleration roughly represents the change of the speed of the object during this time. If it is smaller, the fluctuation of speed will be smaller and the described speed change will be more detailed, thus defining the instantaneous acceleration of particle A at this moment as
Three particles start from the coordinate origin at the same speed, and their positions and curves about time are caused by positive, zero and negative accelerations respectively.
Instantaneous acceleration, referred to as acceleration [1]. Then there is
When moving in a straight line, the vector degenerates into a signed scalar, and its absolute value represents the size of the physical quantity. Positive speed means right and negative speed means left. When the acceleration and velocity are in the same direction (that is, the sign is the same), it means that the object is accelerating, and when it is different, it means that the object is decelerating.
The right picture shows the position curves of three particles with the same speed from the origin of coordinates, which are caused by their positive, zero and negative accelerations respectively. As you can imagine, on a smooth desktop, three wooden blocks slide down the inclined plane, down the horizontal plane and up the inclined plane at the same initial speed.
On the displacement-time diagram, the acceleration is represented by the convexity of the curve, and the positive part of the acceleration is represented by a convex function, and vice versa.
[Edit] Acceleration of spatial curve motion
How to approximate the acceleration vector from the displacement vector is expressed in two different ways. Let particle A move in space, and the vector whose origin O points to A is its vector diameter, then its velocity vector and acceleration vector can be similarly defined as [2].