In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform variable speed linear motion, the following listed% 2 In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform linear motion, which of the following measures are beneficial? A. Make the acceleration of the car as small as possible B. Appropriately increase the number of hook codes hanging under the string C. Under the same conditions, make multiple tapes and choose one of the most ideal ones for measurement and calculation D. Round off the dense points on the paper tape, and then select the counting points for calculation Mainly B option, our teacher said to reduce the number of hook code, why

In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform variable speed linear motion, the following listed% 2 In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform linear motion, which of the following measures are beneficial? A. Make the acceleration of the car as small as possible B. Appropriately increase the number of hook codes hanging under the string C. Under the same conditions, make multiple tapes and choose one of the most ideal ones for measurement and calculation D. Round off the dense points on the paper tape, and then select the counting points for calculation Mainly B option, our teacher said to reduce the number of hook code, why

The pull force in the experiment is equal to the gravity of the hook code, but actually the hook code has acceleration, so it is in the weightless state, and the pull force is higher

What is the dynamic friction and static friction?
Is there any comparison between static friction and dynamic friction?
What is the meaning of interactive pressure?

1: The maximum static friction > dynamic friction
2: Two objects receive pressure from each other. The two objects may not contact each other, but the two forces are equal in any case

What is the static friction equal to? What is the dynamic friction

Now a horizontally placed object is in a static state, and a horizontal force F is applied to it. If it does not move, then the static friction force is f, which is opposite to the front F,
Gradually increasing F, there is always a value f ', which makes the object start to move, then f' is the maximum static friction
The acceleration of the object indicates that f 'is greater than the dynamic friction force!
The formula of dynamic friction: F = μ g, μ is the coefficient, which is related to the specific situation, and G is the physical gravity
Pay attention to f '>'f'

Add an integral to the polynomial x2 + 4 to make it a complete square. The integral that can not satisfy the above conditions is ()
A. 4xB. -4xC. 4D. -4

A. It is a complete square form, so this option is wrong; B, X2 + 4-4x can get x2-4x + 4, can be changed into (X-2) 2; C, X2 + 4 and 4 can get x2 + 8, not a complete square form, so this option is correct; D, X2

If we know the first-order function y = KX + B, when x ≥ 1, y ≥ 1, when x

If we know the first-order function y = KX + B,
When x ≥ 1, y ≥ K + B ≥ 1,
When x

VB two for loop statements to solve
X=0
For i= 1 to 4
For j = 1 to i
x= x+1
next j ,i
Find the loop after the loop and explain how the two for loops

I = 1 J = 1 x = 1 I = 2 J = 1 x = 2 J = 2 x = 3 I = 3 J = 1 x = 4 J = 2 x = 5 J = 3 x = 6 I = 4 J = 1 x = 7 J = 2 x = 8 J = 3 x = 9 J = 4 x = 10 the cycle ends and x = 10

If an electric energy meter is marked with "220V 5A", how many lights can be connected to "PZ 220-60" at most?

The working current of a 60W bulb is about 0.27A, which should not exceed (5 △ 0.27) = 18

Proof of monotone bounded theorem by nested interval theorem
Process and how to take the interval set, how to set the limit

It's meaningless to prove it like this, because it's easier to prove it with the infimum theorem. Let's have a try. Let's study the proof of monotone boundedness theorem with the interval nest theorem: first of all, we need to use the infimum theorem, monotone boundedness must have infimum. Let's suppose that the sequence {an} monotone drops and increases, then there is infimum m, then an ≤ m, thus [...]

How much energy can I save by turning the air conditioner down? How to convert it?

For example, if a one horse air conditioner is installed in a room of 30 square meters, the ambient temperature is minus 5 degrees, and the heating temperature is set at 25 degrees, then you will not reach the temperature after 24 hours. Even if you turn it down to 20 degrees, it is impossible to save electricity, because the air conditioner can not meet the demand at all. Relatively speaking, the configuration is reasonable, the environment is suitable, and the average power saving is 5%, I am not a mathematician and can not provide accurate formulas

Simplified evaluation: (x + y) + (2x + 1 / 2Y) + (3x + 1 / 6y) +. + (9x + 1 / 72y), where x = 1, y = - 9

Original formula = x (1 + 2 + 3 +...) +9)+y(1+1/2+1/6+…… +1/72)
=45x+y(2-1/2+1/2-1/3+…… +1/8-1/9)
=45x+y(2-1/9),
When x = 1, y = - 9, the original formula = 45-9 (2-1 / 9) = 45-18 + 1 = 28