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The formula of velocity is v = △ X / △ T. is v the average velocity or the velocity? What's the difference between the average velocity and the velocity
The velocity is instantaneous, and the average velocity is a period of displacement divided by the total time. When the interval time tends to zero, the instantaneous velocity is equal to the average velocity. The velocity is the magnitude of the velocity
Physical instantaneous velocity
What is the speed of the ball to the bottom of the inclined plane when it passes through the middle of the inclined plane v = 3m / S
The formula used is: vt & # 178; - vo & # 178; = 2As
At the midpoint: 9 = 2A × 0.5s, that is: 9 = as
When at the bottom of the slope: VX & # 178; - vo & # 178; = 2As, and: as = 9
So: VX & # 178; = 2 × 9
That is: VX = 4.242m/s
The vehicle (which can be regarded as a particle) starts from a stationary state and makes a straight line motion with uniform acceleration. It takes 10 seconds to pass a 140 m long bridge. The speed after passing the bridge is 16 m / s. find out (1) what is the speed when it just drives on the bridge head? (2) How far is the bridgehead from the starting point?
(1) The average speed in the process of crossing the bridge. V = XT = 14m / S & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; the average speed of uniform variable speed linear motion & nbsp;. V = V0 + V2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; so V0 = 12m / s, so the speed of the car just on the bridge head is equal to 12m / S. (2) the acceleration of uniform variable speed linear motion a = V − v0t according to the velocity displacement formula V02 = 2aX, it is obtained by substituting the data; &Therefore, the distance between the bridgehead and the starting point is 180m
[physics] instantaneous velocity can only describe the magnitude of velocity, and its magnitude is velocity
I feel that what this sentence describes is correct, but the answer is wrong. It's very tangled
The first half of the sentence is wrong
Definition of instantaneous velocity: the velocity of a moving object at a certain time or a certain position is called instantaneous velocity for short. Instantaneous velocity is a vector. The direction of the instantaneous velocity at a certain time (or passing through a certain position) is the direction of the object's motion at that time (or passing through a certain position)
Definition of instantaneous speed: the size of instantaneous speed, also referred to as speed
So instantaneous velocity can also describe the direction of velocity
Will two objects with the same radius have the same linear velocity or angular velocity?
For example, in a belt device, if the radius of the left and right wheels is different when rotating at a constant speed, are the angular velocities or the linear velocities of any two points on the edge of the left and right wheels equal?
The linear speed is the same
Because the belt drives two wheels to rotate, the distance of the belt is equal, so the linear velocity of the two points is the same, the radius is different, so the angular velocity is different
The angular velocity of points on the same wheel is the same
As shown in the figure, one end of the straight rod with length l can rotate around the fixed axis O, and the other end is placed on the lifting platform. The platform rises at a constant speed v. when the angle between the rod and the vertical direction is α, the angular velocity of the rod is ()
A. vsinαLB. vLsinαC. vcosαLD. vLcosα
The actual motion of the contact point between the rod and the platform, that is, the direction of motion is perpendicular to the rod and points up to the left. As shown in the figure, the velocity component along the vertical upward direction is equal to V, that is, ω LSIn α = V, so ω = vlsin α. So ACD is wrong, B is correct, so B is selected
Find the ratio of velocity, displacement and time in the uniform speed change linear motion of the high one physics
In the same time: V1: V2: V3 ：Vn=1：2：3：… ：n
X1：X2：X3：… ：Xn=1：3：5：… ：（2n-1）
The ratio of time spent by the same person
t1':t2':t3':...:tn'=1:（√2-1）:（√3-√2）:...:（√n-√n-1）
The relationship between linear motion and displacement with uniform speed change
When a car illegally overtakes and drives into the left retrograde road at the speed of 108km / h, it suddenly finds that a truck is coming at the speed of 72km / h 80 meters in front of it. The drivers of the two cars brake at the same time. The braking acceleration is 10m / s square second, and the reaction time of the two drivers is t second. Why does t guarantee that the two cars will not collide?
V1=108km/h=30m/s,V2=72km/h=20m/s,
80>V1t+V2t+V1^2/2a+V2^2/2a=30t+20t+30*30/(2*10)+20*20/(2*10)=50t+65
t
Image processing of uniformly accelerated linear motion
I hope I can help to draw the changes of uniform acceleration linear motion in VT image and XT image, and make some explanations. The more detailed the better. I can also add examples. Thank you
As shown in the figure, figures (a) and (b) are the VT and St diagrams of uniformly accelerated straight-line transport, respectively. Because the relationship between velocity and time is v = V0 + A * t, which is a power equation, it is a straight-line image. And the relationship between displacement and time is s = V0 * t + 1 / 2 * a * T ^ 2, which is a quadratic equation, so the displacement image is a parabola image
High school physics uniform speed linear motion problem
In the low altitude parachute training, when the helicopter hovers 224m above the ground, the paratroopers leave the aircraft to do free fall movement. After a period of movement, open the parachute. After the parachute is unfolded, the paratroopers decelerate at an acceleration of 12.5m/s2. For the safety of the paratroopers, the maximum landing speed of the paratroopers is required not to exceed 5m / S (g = 10), What is the minimum height from the ground? What is the equivalent of falling freely when landing? (2) what is the minimum time for paratroopers in the air?
Three equations, four unknowns, how to find acridine?
(1) Let V 2 = 5 m / s when paratroopers land. The total height of paratroopers is known to be h = 224 M. when the height is set to h, open the parachute and the speed is v 1. After opening the parachute, decelerate the parachute evenly. Free fall process: v 1 & # 178; = 2 g (H-H) after opening the parachute, V 2 & # 178; = v 1 & # 178; + 2 ah
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