When an object moves in a curve, the physical quantity of a certain change is () A. Gravitational potential energy B. velocity C. acceleration D. combined external force

When an object moves in a curve, the physical quantity of a certain change is () A. Gravitational potential energy B. velocity C. acceleration D. combined external force

A. The condition of curvilinear motion is that the external force and velocity are not in the same straight line, which has nothing to do with the gravity of the object, so it has nothing to do with the gravitational potential energy

When an object moves in a curve, the physical quantity of a certain change is ()
A. Gravitational potential energy B. velocity C. acceleration D. combined external force

A. The condition of curvilinear motion is that the combined external force and velocity are not in a straight line, which has nothing to do with the gravity of the object, so it has nothing to do with the gravitational potential energy. So a is wrong; B, the condition of curvilinear motion is that the combined external force and velocity are not in a straight line, and the direction of velocity changes all the time, so the velocity must change when the curvilinear motion changes. So B is correct; C, D, and the resultant force of curvilinear motion must not be zero Under the action of constant force, the object can do curvilinear motion, such as horizontal throwing motion, and the resultant force and acceleration will not change

The constant physical quantity of an object moving in a circle at a uniform speed is ()
A. Kinetic energy B. velocity C. centripetal acceleration D. centripetal force

In the process of uniform circular motion, the linear velocity remains unchanged, the direction changes, the centripetal acceleration remains unchanged, the direction always points to the center of the circle, the centripetal force remains unchanged, the direction always points to the center of the circle, and the kinetic energy remains unchanged

The following physical quantities belong to vector ()
A. Displacement, velocity and time B. force, velocity and distance C. distance, displacement and force D. velocity, acceleration and force

A. Displacement and velocity are vectors with both size and direction. Time is a scalar with only size and no direction, not a vector. So a error B, force and velocity are vectors with both size and direction. Distance is a scalar with only size and no direction, not a vector. So B error C, displacement and force are vectors with both size and direction. Distance has only size and no direction Scalar, not vector. So C error, D, velocity, acceleration and force are vectors with both magnitude and direction. So D is correct, so D is selected

Sin ^ n x * cos ^ m x from 0 to 2pi
The first step of the answer is to say "it can be obtained from the integral property of periodic function", and then change the integral limit to - pi to PI, and the rest remain unchanged?
The second step of the answer is "when n is odd, the integrand is odd, so the integral is equal to 0". Why is the integrand odd? What are the parity conclusions of sin ^ n x and COS ^ n x?
In the third step of the answer, "when m is odd, M = 2K + 1" is transformed into sin ^ n x * (1-xin ^ 2 x) ^ k dsinx's integral from - pi to + PI. Then how can this formula be equal to 0?
The answer is too brief

First, you are wrong. The period of the integrand is 2 π, but as long as the length of the integral limit is one period, it can be changed into any integral limit
Second, SiNx is an odd function, its odd power is also an odd function, and even power is an even function
Thirdly, ∫ (SiNx) ^ n [1 - (SiNx) ^ 2] ^ KD (SiNx)
=∫(sinx)^n-(sinx)^(n+k)d(sinx)
=[(sinx)^(n+1)/(n+1)-(sinx)^(n+k+1)/(n+k+1)]
And sin (- π) = sin π = 0
So the original formula = 0

[(sin x-cos x) / (SiN x + cos x)] ^ 4 finding definite integral interval 0 - π / 4

[（sin x-cos x）/(sin x+cos x)]^4 =[(1-tgx)/(1+tgx)]^4=[tg(x-45)}^4=[sec^2(x-45)-1]^2
The above two answers are wrong

Cos (x) * (sin (x)) ^ 2 * D (sin (x)), how to calculate the definite integral from 0 to 90,

cos(x)*(sin(x))^2*d(sin(x))
=cos(x)^2*(sin(x))^2*d(x)
=1/4*(sin(2x))^2*d(x)
=1/8*(sin(2x))^2*d(2x)
Simplify to this, you can forget it

Finding definite integral ∫ (0 to π / 2) [cos (x / 2) - sin (x / 2)] ^ 2DX
What trigonometric transformation is applied to?

[cos(x/2)-sin(x/2)]²=[cos²(X/2)+sin²(x/2)]+2sin(x/2)cos(x/2)=1+sinx∫(π/2,0)[cos(x/2)-sin(x/2)]^2dx=∫(π/2,0) 1+sinx dx=x|(π/2,0)-cosx|(π/2,0)=(π/2)+1

How to find the definite integral of (COS ^ 2 x)
Such as the title

cos²x=(1+cos2x)/2
So ∫ cos & sup2; xdx = ∫ 1 / 2DX + 1 / 2 * ∫ cos2xdx
=x/2+1/4*∫cos2xd(2x)
=x/2+1/4*sin2x
=(2x+sin2x)/4
The constant C will not be added to the definite integral. You can substitute the upper and lower limits of the integral

Definite integral ^ (PAI / 2)_ 0 e^x*sinxdx
What is the sum of the square of the definite integral e multiplied by the sine of X in the half pie to zero?

It's π / 2 - > 0, or 0 - > π / 2. I feel that π / 2 - > 0 is strange. The building owner should do more part integration~~~
Here I don't write the upper and lower limits of the integral, I will bring in the result later, so as to avoid trouble, you are not good-looking~~~~
Let ∫ e ^ xsinxdx = t
∫e^xsinxdx
=∫sinxde^x
=e^xsinx-∫e^xdsinx
=E ^ xsinx - ∫ e ^ xcosxdx
=e^xsinx-∫cosxde^x
=e^xsinx-e^xcosx+∫e^xdcosx
=e^xsinx-e^xcosx-∫e^xsinxdx
=e^xsinx-e^xcosx-T
The formula t = e ^ xsinx-e ^ xcosx-t is obtained
Transfer term to simplify t = e ^ X / 2 (SiNx cosx), bring in the upper and lower limits of the integral to calculate - 1 / 2 (1 + e ^ π / 2)
By the way, I didn't notice that this is a generalized integral problem, which means that there is something wrong with π / 2 - > 0 ~ ~ ~ but the result should be no problem ~ ~ ~ replace 0 with B, and finally bring the upper and lower limits of the integral into the calculation. Just take the limit B - > 0 for B ~ ~ ~ ~ ~ LIM (B - > o) e ^ X / 2 (SiNx cosx) | π / 2 - > 0