Uniform linear motion is essentially along the sphere of the universeUniform circular motion。v=wR
Uniform linear movement is the simplest mechanical movement, which refers to the movement along a straight line with constant speed (i.e. constant speed).In uniform linear motion, the distance is proportional to time, and is calculated by the formula s=vt.
For an object moving in a uniform straight line, in different displacement or time periods, the ratio of displacement to time is a fixed value, which is the speed of the motion.(Note: the speed is a fixed value, which refers to the sum of the constant speed andDirection of movementBoth are unchanged, because the velocity is a vector, with size and direction.)The speed directly reflects the speed of the object movement.In uniform linear motion,average velocityandInstantaneous velocityIs equal, the size of average speed and averagerateIt is also equal.
acceleration
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1. The acceleration of an object in uniform motion is zero.
2. The combination of ideal state and practice: uniform linear motion is not common, because the condition for an object to move in a uniform linear motion is that it is not subject to external forces or the sum of external forces is zero, but we can approximately regard some motions as uniform linear motion.For example, the skater's slide after stopping the force, the movement of the customer standing on the escalator in the mall, and so on.We can use the formulav=s/tGet theirMovement speed。Where, s is displacement, v is velocity and isConstant vector，T is the time taken for displacement s.It can be seen from the formula that the displacement is time dependentPositive proportional function: Displacement is proportional to time.
3. When the object is in uniform linear motion, the force on the object is balanced.
4. When an object moves mechanically, it can be divided into linear motion and curvilinear motion according to the straightness of the motion path.In linear motion, according to whether the speed changes, it can be divided into uniform linear motion and variable linear motion.
Important points
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(1) Speed means the speed of the objectphysical quantity, speed can be represented by the symbol V.stayInternational System of Units (SI)The main unit of velocity is m/s, which is read as meters per second.The common units are km/h, m/min, etc.
(2) The speed of an object moving at a uniform speed in a straight line remains unchanged. Therefore, if you know the speed at a certain time (or a certain distance), you will know its speed at any time or at any moving point.
(3) When an object is subjected to two or more forces, if it can remain stationary or move at a constant speed in a straight line, we say that the object is in theEquilibrium state。
(4) You can't use the formula mathematicallys=vtIt is understood that the speed of an object's movement is proportional to the distance and inversely proportional to time.The characteristic of uniform linear motion is that the magnitude and direction of instantaneous velocity remain unchanged, and the acceleration is zeroIdealizationThe movement of.
(5) Charged particles are affected byConstant forceandLorentz forceWhen moving under the joint action, as long as it is a linear motion, it must be a uniform linear motion.(Cause: force like F Luo will change with the change of speed, that is, speed directly affectsResultant force, the resultant force directly affects the acceleration, that isDirection of movement。）
