The resistance of a locomotive in motion is constant A. If the power increases uniformly with time, the speed will increase uniformly with time. D. if the speed increases uniformly with time, the power will increase uniformly with time

The resistance of a locomotive in motion is constant A. If the power increases uniformly with time, the speed will increase uniformly with time. D. if the speed increases uniformly with time, the power will increase uniformly with time

A. If the acceleration is decreasing, the direction of acceleration is opposite to the direction of velocity, f-f = ma. If the acceleration is decreasing, the traction force is increasing, and the power may be increasing. So a is correct. B, the power is decreasing, and if f also decreases, the speed may increase. So B is correct. C, if the power increases uniformly with time, we know from P = FV = fat that only when f is constant, the speed increases uniformly with time D. if the speed increases uniformly with time, the acceleration is constant and the traction force is constant, then p = FV = fat, and the power must increase uniformly with time

The autocorrelation function and power spectral density function of sine signal x (T) = asin (WT + φ) are obtained

The purpose of this paper is to provide the [x (T1) x (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (t (T)))) (2 + 1) 1)) (A / 2 / 2) cossw (t (t 2-T 2-1)) (2-1)) (cosw (t (t 2-1)) (2-2-2-2-2-1)) (cosw (t (t 2-1)) (2-2-2-1) + 2-1) + 1) + 0 it's not easy
Fourier transform cosw τ π [δ (W-W) + δ (W + W)] so the autocorrelation function is R (τ) = (A2 / 2) cosw τ, and the power spectral density is PX (W) = (π A2 / 2) [δ (W-W) + δ (W + W)]
(A2 is the square of a)

When is the Fourier transform of autocorrelation function power spectral density and energy spectral density
Does autocorrelation function have a special definition for periodic function? Remember that there seems to be a definition for calculating limit. Forget it, or say that both periodic function and aperiodic function use the same definition. In addition, autocorrelation function and signal energy spectral density or power spectral density are Fourier transform. So when is power spectral density and energy spectral density?

The power spectrum is the energy spectrum

The difference between power function and energy function

Classmate, I don't quite understand what you want to ask
The function of beginning and ending is the energy function
A function that has no beginning and no end is a power function
,
Because a continuous function with a beginning and an end can integrate and calculate the continuous sum, and then calculate the energy
On the contrary, the power function can not be found

The equation of motion is s = T ^ 3 + 2T ^ 2-1, when t = 2,

V=dS/dt=3t^2+4t=20
a=dV/dt=6t+4=16

The equation of motion of a particle s = sin2t to find the acceleration of the particle (by derivative)

Y '= 2cos2t (velocity)
Y '' = - 4cos2t (acceleration)

In mathematics, the relation between the displacement s of a derivative and time is s = 5-3t square, then the average velocity of the particle in the time period (1,1 + triangle T) is

Average velocity v = - 6-3 Δ t

The motion equation of the particle is s = 3T + 1 (displacement unit: m, time unit: s), and the velocities of T = 1 and 2 are calculated respectively,
The branch is to adopt

s=3t+1
v=ds/dt=3 m/s
V is a constant, uniform motion
When t = 1 and 2s, the velocity is 3m / s

Finding the minimum of M = 2-sin θ / 1-cos θ
Do me a favor

M = under 2-radical (sin ^ 2 θ / (1-cos θ) ^ 2) = under 2-radical [(1-cos ^ 2 θ / (1-cos θ) ^ 2] = under 2-radical [(1 + cos θ) / (1-cos θ)] = 2-cot θ / 2
This minimum can be infinitesimal. It should be right

P is a point on the curve X = sin θ + cos θ y = 1-sin 2 θ (θ∈ [0,2 π] is a parameter). The minimum distance from P to Q (0,2) is___ ．

The general equation of the curve is y = 2-x2, let P (x, 2-x2), then p to point Q (0, 2)