The relationship between velocity and displacement of linear motion with uniform velocity An ice hockey glides on the ice, passes two distances L in turn, and continues to move forward. The time t for it to pass through the first distance is 2T, and the time for it to pass through the second distance is 2T. If the ice hockey moves in a straight line at a constant speed on the ice, the speed of the ice hockey at the end of the first distance is calculated Take the starting time of ice hockey passing point a, B as the end of L, C as the end of the second section From a to B: l = (V0 + V1) / 2 * t (1) From B to C: l = (V1 + V2) / 2 * 2T (2) From a to C: 2L = (V0 + V2) / 2 * 3T (3) According to the above formula, V1 = 5L / 6T From the above equation (1) (2) (3), we can get: V1 = (5L) / (6T) how to calculate this step I need to know the questions in the supplementary questions

The relationship between velocity and displacement of linear motion with uniform velocity An ice hockey glides on the ice, passes two distances L in turn, and continues to move forward. The time t for it to pass through the first distance is 2T, and the time for it to pass through the second distance is 2T. If the ice hockey moves in a straight line at a constant speed on the ice, the speed of the ice hockey at the end of the first distance is calculated Take the starting time of ice hockey passing point a, B as the end of L, C as the end of the second section From a to B: l = (V0 + V1) / 2 * t (1) From B to C: l = (V1 + V2) / 2 * 2T (2) From a to C: 2L = (V0 + V2) / 2 * 3T (3) According to the above formula, V1 = 5L / 6T From the above equation (1) (2) (3), we can get: V1 = (5L) / (6T) how to calculate this step I need to know the questions in the supplementary questions

L=V0t-1/2at^2
2L=V0*3t-1/2a(3t)^2
V0=7L/6t
L=Vt*2t+1/2a(2t)^2
2L=Vt*3t-1/2a(3t)^2
Vt=L/6t
V=√[V0^2+Vt^2]/2=5L/6t
Your question
From a to B: l = (V0 + V1) / 2 * t (1)
From B to C: l = (V1 + V2) / 2 * 2T (2)
From a to C: 2L = (V0 + V2) / 2 * 3T (3)
(1) We get 2L = v0t + v1t
v0=2L/t-v1
(2) We get l = v1t + v2t
v2=L/t-v1
By introducing the formula (3) 2L = (V0 + V2) / 2 * 3T
2L= （v1-2L/t+v1-L/t)/2 *3t = （2v1-3L/t)/2 *3t
2v1=3L/t-4L/3t=5L/3t
v1=5L/6t

As shown in the figure, if the generatrix ab of the cone is 6 and the bottom radius CB is 2, then the degree of the center angle α of the sector in the side expansion view is ()
A. 90°B. 100°C. 120°D. 150°

∵ base radius CB = 2, ∵ perimeter of base circle of cone = 2 π· 2 = 4 π, ∵ 4 π = α· π· 6180, ∵ α = 120 °. Therefore, C is selected

Fall 2012. People's education press. Rational division. Exercises 3 to 6. Some help me get

Our is the version of Beijing Normal University!

The perimeter ratio of a and B is 2:3. The area of one circle is 12 square centimeters. What is the area of the other circle?

12 divided by 2 equals 6, 6 times 3 equals 18. 12 divided by 3 equals 4, 4 times 2 equals 8
A: it could be 18, it could be 8

What is the sum of the areas of all sides n of a six prism

Side area = 6 × (5 × 4) = 120 square cm

How to simplify y = 4sin (x - π / 4) cos (x + π / 4)!

y=4sin(x-π/4)cos(x+π/4)
=4sin (x - π / 4) sin [π / 2 - (x + π / 4)] / the latter term uses the remainder formula
=4sin(x-π/4)sin(π/4 -x)
=-4sin²(x-π/4) /sin(-a)=-sina
=-2 [1-cos (2x - π / 2)] / using the double angle formula: 2Sin & # 178; a = 1-cos (2a)
=-2[1-cos(π/2 -2x)] /cos(-a)=cosa
=-2[1-sin(2x)]
=2sin(2x) -2

Sum 1 * 4 + 2 * 5 + 3 * 6 +... + n * (n + 1) =?

There is a problem with this problem: at last, it should be added to n {n + 3}, and each term should be directly reduced to n * n + n * 3. Then sum them separately

What sentences use the dash as a supplementary
Which sentences use the function of Dash "supplementary explanation"? Who answers that one yuan will be awarded? I'm Li Xinqian from qilipo primary school,

This is a common use of dashes
For example:
(1) On the morning of August 1, 1927, a commander waved his left hand to announce the uprising to the soldiers. The soldiers held up the signal of the Uprising - the lantern. The bright red flag was raised, the horses were roaring, the working people were helping to carry the bullets, and the soldiers were shouting excitedly
(2) Stepping into the golden copper gate, through the wide hall and cloakroom, you will arrive at the central hall, the hub of the city hall
(3) Oh, this is the last child she took, the 19th
(4) She said with a smile: "sweet potato porridge - our new year's Eve dinner."
to make clear:
(1) "Lantern" explains the tool used as "signal" of uprising and the concrete things held by soldiers
(2) The "central hall" explains the contents of the "hub part of the city hall building"
(3) "The 19th" explains who the last child she had
(4) "Our new year's Eve meal" is to explain "sweet potato porridge" as food in a specific time, emphasizing the material poverty of that time
There are Himalayas, the highest mountain in the world, and Mount Everest, the highest mountain on the earth
If an explanatory or supplementary sentence is inserted in the middle of the sentence, a dash can be used before and after it
For example: "in addition to the eight major planets Mercury, Venus, earth, Mars, Jupiter, Saturn, Uranus and Neptune, the solar system also has 40 satellites and numerous asteroids, comets and meteoroids."
"Intuition - though it's not always reliable - tells me that something may be wrong."
"All governments - autocratic or Republican - expelled him."
Parentheses also indicate explanations, but dashes lead to explanations that are part of the text and are more important information to be read out. The explanations in parentheses are not the text but notes. Without them, the integrity of the sentence will not be affected and it is not necessary to read them out in conjunction with the text. Moreover, sometimes there are other punctuations before dashes
When Yang Er Sao saw this incident, she took the dog to kill (this is our chicken raising equipment. There is a fence on the wooden plate. It contains food inside. The chicken can stick into its neck to peck, but the dog can't. She can only look at it and die of anger). She ran like a fly. Thanks to her high and low feet, she ran so fast. (Lu Xun's hometown)
After a while, another one said, "Why are you all gone? It's rare for you to come here and have a free bath, but you don't have to play for a while." Oh, where are my clothes? Who has seen my clothes? "
Although brackets are used to indicate supplementary statements, the supplementary statements indicated by dashes are part of the text and need to be read out. The supplementary statements indicated by brackets are not the text and can not be read out, A dot at the end of a sentence is often used in front of a dash to indicate the integrity and independence of the words and meaning before the dash

Let F1F2 be the left and right focus of the ellipse x ^ 2 / 4 + y ^ 2 = 1 respectively. If a straight line L crosses the ellipse at two different points a, B, OA and is perpendicular to ob through the left focus F1, calculate ab

Let a (x1, Y1), B (X2, Y2)
c^2=a^2-b^2=4-1=3
c=3^1/2
F1(-3^1/2,0)
Straight line L: y = K (x + 3 ^ 1 / 2)
x^2+4y^2=4
x^2+4k^2(x+3^1/2)^2=4
(1+4k^2)x^2+8x3^1/2k^2x+(12k^2-4)=0
x1+x2=-8x3^1/2k^2/(1+4k^2)
x1x2=(12k^2-4)/(1+4k^2)
OA=（x1,y1),OB=(x2,y2)
OAxOB=x1x2+y1y2=x1x2+k(x1+3^1/2)k(x2+3^1/2)=0
(1+k^2)x1x2+3^1/2k^2(x1+x2)+3k^2=0
(1+k^2)x(12k^2-4）/(1+4k^2)+3^1/2k^2(-8x3^1/2k^2)/(1+4k^2)+3k^2=0
11k^2=4
k^2=4/11
x1+x2=-32x3^1/2/27
x1x2=4/27
AB=(1+k^2)^1/2x/x1-x2/
=(1+4/11)^1/2x[(x1-x2)^2]^1/2
=(1+4/11)^1/2x[(x1+x2)^2-4x1x2]^1/2
=(15/11)^1/2x[(-32x3^1/2/27)^2-4x4/27)]^1/2
=(15/11)^1/2x[(32^2x3/27^2-16/27)]^1/2
=(15/11)^1/2x[2640/27^2]^1/2
=(15/11)^1/2x4/27x(15x11)^1/2
=4/27x15=60/27=20/9
Problem Solver: Huang Xidong time: August 13, 2013

The circumference of a rectangle is 120 decimeters, and the length is 36 decimeters?

A: the area of a rectangle is 864 square decimeters