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Speed is an object_____ A physical quantity, which is numerically equal to the position of the object_____ .
Speed of movement
The ratio of distance to time per unit time
All these things are like using the velocity V1 and V2 of two adjacent same time periods t to calculate the acceleration
F = ma (F is the combined external force)
Vt = V0 + at (VT is the final velocity and V0 is the initial velocity)
Vt & # 178; - V0 & # 178; = 2As (VT is the final velocity, V0 is the initial velocity)
S=aT²
A = RW & # 178; (centripetal acceleration)
The last one is "divide the difference of adjacent displacements at the same time by the square of time to get the sum of two accelerations and divide by 2 to get the average acceleration"?
What is the physical meaning of unit time
The distance per unit time means that the distance is shorter than the time; the distance per unit time is shorter than the time
How to define "time" in physical sense?
Time is a parameter used by human beings to describe the process of material movement or event occurrence. The determination of time depends on the law of periodic change of material that is not affected by the outside world. For example, the moon's cycle around the earth, the earth's cycle around the sun, the earth's rotation cycle, the atomic oscillation cycle, etc, The universe starts from a starting point, which is also the starting point of time
All moving objects have a common feature, that is, motion. Mechanical motion, thermal motion, biological motion and other motions are corresponding, and this "motion" is time. Generally, the "motion" of mechanical motion, i.e. s / V, i.e. time, is used to represent all objects and the time of all motions, Light motion and other motion can express time. To be exact, S / V of mechanical motion means the amount of motion and the amount of motion
Time is a variable, an increment, time is the amount of movement. Time is the amount of movement. The essence of time is the amount of movement
The essence of time: time is a measure of the sequence or duration of events
The origin of time is the existence process of things. Time is the natural attribute of all things. Time is the representation of existence, the record of process, and the parameter of describing the existence process and its fragments
What is the definition of time in physics
Definition of time: human beings summarize the concept of time in their life, which is rooted in the sequence of events in daily life. Of course, what people get in life is not only the concept of the sequence of events, but also the concept of time interval. This concept comes from the comparison of two processes - for example, two things start at the same time, We can see here that people use measurable process to measure abstract time. In physics, time is also defined by physical process, first in a reference frame (inertial frame, or non inertial frame), But the space range of the process is infinitesimal, take a physical process, set it as time unit, and then compare this process with other processes to measure time. But the concept of simultaneity must exist in the measurement of time (i.e. the above comparison process). There is a problem of simultaneity at the beginning of the process, There is also a problem of simultaneity at the end of the process - the simplest example: we require the athlete to start running when the starting gun is fired, and the timekeeper must start timing at the same time, and stop timing when the athlete reaches the finish line, It makes classical Newtonian mechanics, special relativity and general relativity have different "time". The intuitive concept tells us that anyone can reach an agreement on whether an event is simultaneous (maybe some people will cheat others, causing a situation similar to that in detective stories or political novels, but this is the expression of human "high intelligence", In relativity, the state of the observer's motion causes the change of simultaneity. In other words, observer 1 moves with V1 and thinks that two things are at the same time. Observer 2 moving with V2 may think that they are not at the same time. This leads to the relativity of time measurement
The definition of time in Physics
If the question says "in five seconds", do you think zero seconds is one second?
On the time axis, 0 is the time, a point. Take 0 as the starting point of timing. 0 is the beginning of 1 second, counted as 0 second, and then the end of 1 second. This means within 1 second
Speed: a physical concept
Definition of speed: the ratio of the displacement of an object moving at a constant speed to the time it takes is called speed
Notice the displacement!
That means there's a problem, for example
The speed of light is the propagation speed of light wave or electromagnetic wave in vacuum or medium
Now there is a point light source. There is a mirror at the distance of 3 * 10 ^ 8m from the light source. The light is emitted to the mirror at the speed of 3 * 10 ^ 8m / s, and it takes 2 s to pass the distance of 6 * 10 ^ 8m. Because it is reflected back to the position of the light source, but its displacement is still 0 m, so we say that the average speed of this time line is 0 m / s
So I'm speechless
First floor, please. Didn't I go in? C = 0 m / 2 s = 0 m / s, the average speed of light is 0 m / s
…… Yes, I admit that the speed of light is 3 * 10 ^ 8m / s, but I don't admit that the speed is 3 * 10 ^ 8m / s
"Speed" in life and "speed" in Physics
It's not the same thing
The speed of light is the speed of light,
The evidence is that speed in physics has not only size but also direction
But not every time the speed of light is mentioned, the direction of the speed of light must be mentioned
Because the speed of light is the "speed" in physics
What is the meaning of "△" in the chapter of velocity in physics?
Small change
v=△s/△t
Δ s / △ t is the limit value when Δ t tends to zero
What is frequency? What is the physical meaning of frequency?
Frequency indicates the speed of a repetitive event, unit: Hz, 1Hz = 1 / s, which indicates how many times an event occurs in a second. For example, 5Hz means that the event occurs five times in a second
What is the meaning of speed in physics
Speed is the distance divided by time, speed is the displacement divided by time, displacement is the linear distance from the starting point to the end point, and distance is the distance of motion [can be a straight line or a curve]
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