![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
The light bulb marked with pz220-50 is connected to the 110V circuit. How to calculate the actual power It's a multiple choice question. A. 40W B. 20W C. 12.5W D. can't judge
C 12.5wpz220-50 means the rated power is 50W, the rated voltage is 220V, that is to say, when the voltage is 220V, the power is 50W, the rated current is I = P / V 50 / 220 0.227a, so the bulb resistance is r = u / I = 969 ohm, so under the voltage of 110V, the current is I = u / R 0.114, and the power is
It is known that the elastic stiffness coefficient of a spring is k = 10, and the original length of the spring is 10. When a weight of 500N is hung under the spring, how far does the spring extend?
Let the unit of K be n / cm and the unit of spring length be cm
Because: Mg = KX & nbsp; so the spring elongation x = mg / k = 500 / 10 = 50cm
The spring extends to 50 + 10 = 60cm
The area formula of isosceles right triangle
An isosceles right triangle scarf, its right side is 8 decimeters, find its area
Because it's an isosceles right triangle
And a right angle must be its vertex
So the area is 8 times 8 divided by 2 = 32
75% of 20kg, just ()% of 30kg
50
When two rational numbers are added, subtracted, multiplied, divided, and multiplied, the result is still true
The result is still rational
On the horizontal ground, pull the trolley with 100N weight by 50N horizontal pulling force to make the trolley move forward 5m in the horizontal direction, and the work done by the pulling force is equal to () J
Why do you want 5m * 50N instead of 100N * 5m
100N is the direction of gravity. It moves horizontally without vertical movement, and gravity does no work
Let Sn be the sum of the first n terms of the arithmetic sequence (an). If S3 / S6 = 1 / 3, find S6 / S12 =?
S3=(a1+a3)*3/2=(2a1+2d)*3/2=3a1+3dS6=(a1+a6)*6/2=(2a1+5d)*3=6a1+15dS3/S6=1/36a1+15d=9a1+9da1=2dS6=6a1+15d=27dS12=(a1+a12)*12/2=(2a1+11d)*6=90dS6/S12=27/90=3/10
An air vehicle is driving along a straight line at a speed of 18m / s, and suddenly accelerates at an acceleration of 1m / S2. Find the speed of the vehicle when it accelerates for 18m. The process should be solved in detail
X2-18 × 18 = 2 × 1 × 18, x = OK,
Xiao Ming and Zhang Hua Run the 100 meter race. Xiao Ming reaches the finish 10 meters ahead of time. If Xiao Ming is 10 meters behind the start, who will reach the finish first
Xiaoming arrives first V is speed t is time first V Xiaoming = 100 / T Xiaoming V Zhanghua = 90 / T Zhanghua where t Xiaoming = t Zhanghua second 100 / V Zhanghua = t Hua s Xiaoming = t Hua * V Xiaoming = 100 / V Zhanghua * 100 / T Xiaoming = 100 * t Zhanghua / 90 * 100 / T Xiaoming = 10000 / 90 = 111.1 the speed of the two players remains the same in the two competitions
Given that one root of the equation X2 - (k2-9) x + k2-5k + 6 = 0 is less than 1 and the other root is greater than 2, the value range of real number k is obtained
Let f (x) = X2 - (k2-9) x + k2-5k + 6, then ∵ one root of the equation X2 - (k2-9) x + k2-5k + 6 = 0 is less than 1, the other root is greater than 2, ∵ f (1) < 0 & nbsp; and f (2) < 0, ∵ 12 - (k2-9) + k2-5k + 6 < 0 and 22-2 (k2-9) + k2-5k + 6 < 0, that is, 16-5k < 0 and K2 + 5k-28 > 0, then K ∵ is obtained
RELATED INFORMATIONS
- 1. On the number axis, points a and B represent rational numbers a and B respectively. The origin is just the midpoint of AB, a / 2012b=
- 2. English translation Teach me
- 3. Two cars leave from a and B at the same time. Five hours later Mathematics problems in grade six of primary school Two cars leave from a and B at the same time, and meet at the midpoint of 30 kilometers after five hours. How many kilometers does the fast train travel per hour and the slow train travel per hour
- 4. The two passenger and freight cars leave each other at the same time from a and B, and meet at a distance of 3km from the midpoint. The speed of the bus is 9 / 10 of that of the truck. How many kilometers are there between a and B?
- 5. It took 9 hours for the car to go from a to B and then return to A. It took 100 kilometers per hour to go and 80 kilometers per hour to return. The distance between the two places was? 1000 km
- 6. X1, 2x... X2011 are all positive numbers, a = (x1 + x2... + x2010) (x2 + X3... + x2011) B = (x1 + x2... + x2011) (x2 + X3... + x2010) Compare the size of a and B
- 7. (x + 4) absolute value + (x + 3) absolute value + (x + 1) absolute value + (x-1) absolute value + (x-3) absolute value has a minimum? What is the minimum?
- 8. If the equation (x-1) sin has four different roots x1, X2, X3 and X4 on (- 1,3), then the four roots are added If the equation (x-1) sin has four different roots x1, X2, X3 and X4 on (- 1,3), then what is the sum of the four roots?
- 9. Let X1 and X2 be two of the equations x ^ 2-2008x-1 = 0, and find (x2) ^ 2 + 2008 / x1
- 10. Write two products and sum of 2008x & # 178; - 2007x-2009 = 0, x1 × x2_____ ,x1+x2_______ Let two of the equations 15x & # 178; + 20x-9 = 0 be X1, X2, then X1 & # 178; + x2 & # 178=_______
- 11. As shown in the figure, the constant power supply voltage is 3V, the resistance R1 = 10 Ω, R2 = 30 Ω, when the switch is off, the ratio of A1 and A2 of the ammeter is; when the switch is closed, the ratio of A1 and A2 of the ammeter is Well, the first line is the power supply, the right between the first line and the second line is A1, the second line is R1 and A2, and the third line is R2 and s switches
- 12. The voltage of a section of resistor is 4V, and the current passing through it is 0.2A. With the last resistor, the current in the trunk increases by 0.4A. Ask r sum r?
- 13. The rated voltage is 220 V, the frequency is 50 Hz, the rated power is 880 W, and the volume is 2 L. what is the resistance of this electric kettle when it works normally? Please write down the process,
- 14. Let a 1, a 2, a 3, a 4 be linearly related, and a 2, a 3, a 4, a 5 be linearly independent. Let a 1 be linearly expressed by a 2, a 3, a 4
- 15. If the diagonal of the rectangle is 20cm, the area is 25 and the root is 3cm2, the tangent value of the acute angle between the two diagonal lines is?
- 16. What is the value range of X that makes the formula √ - 2x + 3 meaningful? Please hurry`` Is the root of the root number``
- 17. The bottom of a parallelogram is 7.8cm, the height is 4.5cm, and its area is (), which is equal to its bottom The base of a parallelogram is 7.8cm, the height is 4.5cm, its area is (), and the triangle area with the same base and height is ()
- 18. As shown in the figure, AB is the diameter of ⊙ o, extend AB to point P so that ab = 2bp, make a tangent line of ⊙ o through point P, the tangent point is C, connect AC, then ∠ cap=______ ．
- 19. Simple operation of 37 * 6 + 21 * 18
- 20. A simple and convenient method for the determination of trace elements