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The first volume of junior high school biology textbook content, urgent
Don't rely on others all day long. Do you feel more successful if you do it yourself? I'd better write down the final review materials of biology on the first day of junior high school unit 1 biology and biosphere Chapter 1 understanding biology section 1 biological characteristics 1 biological characteristics: 1. Biological life needs nutrition 2. Living things can breathe 3. Be able to excrete
First volume of junior high school biology book 110 top
I can give you some information. You can put it in yourself. We have also written it. It's very good to write it. Most cactus grow in arid environment. Some are columnar, more than 10 meters high, weighing about 20-30 thousand jin. They stand tall and magnificent. Some cactus with thorns have a life span of more than 500 years and can grow into diameter
On energy transformation (Junior High School Physics)
What can gasoline engine drive motorcycle at high speed? Why
Conversion of internal energy into mechanical energy
When an object falls freely and contacts the spring to the lowest point, which point has the greatest acceleration?
The lowest point
Let the supporting force equal to the gravity of the object when the spring compresses X. if the object is released from the natural length of the spring, the 2x speed of the downward movement of the object will just decrease to zero. If the object is released from a high place, the compression of the spring will be greater than 2X, and the supporting force of the spring will be greater than twice the gravity, that is, the resultant force will be greater than gravity, and the object will move vertically upward
Why is the frequency of alternating current 50 Hz in China
Because the rotating speed of generators in China is 3000 rpm, that is 50 revolutions per second, that is, the alternating current changes 50 times per second, so the frequency of alternating current is 50 Hz
If two forces F1 and F2 are applied to both ends of the spring scale, and F1 is greater than F2, what is the indication number of the spring scale? Why?
You can't use this force. When F1 is greater than F2, the spring is pulled away
So the spring will accelerate in the direction of F1
If you think the spring is balanced at this time, the number on the scale should be 2 times F2
I haven't done physics problem for a long time, I don't know, right
I knew more when I was in high school
The circumference of an isosceles triangle is 48 cm, and the height of the bottom is 3 cm longer than half of the bottom
What's the length of the bottom
Let the base length be B, then 2A + B = 48, (3 + B / 2) ^ 2 + (B / 2) ^ 2 = (48-b) ^ 2 / 4
12b+96b=48*48-36
b=21
The bottom edge is 21 cm long
When a constant force is applied to an object with mass ma, the acceleration of the object is AA. When the force is applied to an object with mass MB, the acceleration of the object is ab. if the force is applied to an object with mass ma + MB, what is the acceleration
The answer is (AA * AB) / (AA + AB)
How to set formula in Excel table
As shown in the figure, how can I set the formula in column d to automatically generate the daily balance?
D2
=IF(AND(B2"",C2""),SUM(B$2:B2)-SUM(C$2:C2),"")
Drop down to copy formula
The friction coefficient between the object with mass m = 4kg and the ground is u = 0.4. Under the action of constant force F = 50N at an angle of 37 degrees to the horizontal
When f is removed 4 m to the right from standstill, the object stops just after 9 m to find 1. The work of pulling force F 2. What is the work of friction in acceleration and deceleration? 3. The total work of resultant force in the whole process
1、w=FSCOS37 =160J
2. Acceleration stage: fsin37 + n = mg, so n = 10N
W = - UNS = - 16J, u is the friction coefficient
Deceleration phase w = - umgs1 = - 144j
3. The total work is equal to the increment of kinetic energy, so it's zero. Or the sum of the three works is 160-16-144 = 0
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