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8 meters, eyes 0.08 meters from the top of the head, standing in front of the vertical plane mirror, he wants to see the image of his feet Drawing
Height of mirror from ground: (1.8-0.08) / 2 = 0.86
To see the whole body, the mirror should be at least 1.8-0.08-0.86 + (0.08 / 2) = 0.9 meters long
Xiao Ming is 1.6m tall. He stands 3 meters in front of the plane mirror. What's his height?
The answer is 1 meter... But why?
Obviously, the answer is 1.6m, and the characteristic of plane mirror imaging is equal size and upright virtual image
Your answer must be wrong
It is possible that the answer is wrong. To learn physics well, one must have the spirit of questioning!
Xiao Ming is 1.7 meters tall and stands one meter in front of a plane mirror placed vertically. The height of his image in the mirror is equal to several meters
1.7m
Because the image of the object in the plane mirror is equal to the size of the object
A person with a height of 1.8m is standing 3m in front of the plane mirror. At this time, the distance between him and his image is ﹤ M
The answer is 3M. Why?
Does it have anything to do with height? The saying of 3 meters ignores the distance between the image and the mirror. In fact, the distance between the image and the mirror is equal to the distance between you and the mirror. In other words, the answer is 6 meters
When we pass the street lamp at night, we will form a shadow on the ground. The reason is that________________ ,
The length of the shadow will change. When you approach the street lamp, the shadow will change__________ After the streetlights__________ (insert "lengthen" or "shorten")
When we pass the streetlights at night, shadows will form on the ground. The reason is that light travels in a straight line
The length of the shadow will change. The shadow will be shorter when approaching the street lamp, and longer when passing the street lamp (fill in "longer" or "shorter")
Cuole upstairs --
5 m Xiaodong stands 2.5 m in front of the plane mirror. When he leaves the plane mirror at the speed of 1 m / s, what is the height of the image?
It's 1.5 meters. The flat mirror is the same size,
If a person moves away from the mirror for 2S at the speed of 1m / s, what is the distance m between the person and the image? What is the height m of the image?
If the person moves away from the mirror for 2S at the speed of 1m / s, the person is 2 meters away from the mirror
Because the distance between the image and the object is the same, the distance between the image and the mirror is 2 meters, so the distance between the person and the image is 4 meters
What's the height of the image m? The height of the image is equal to the height of the object, but you didn't say the height of the object, so you can't know the height of the image
If someone is 5 meters in front of a plane mirror placed vertically, his image in the mirror is 5 meters away from him. If he moves in the direction parallel to the plane mirror at a speed of 1 m / s for 3 s
Then the velocity of the image relative to human is m
It's like 10 meters away from him
When moving parallel to the mirror, the distance between the image and him is still 10 meters, so the speed of the image relative to human is 0
When checking the vision, the distance between the eye and the vision chart should be 5 meters. If a person observes the vision chart through the plane mirror, when the distance between the vision chart and the plane mirror is 3 meters, the distance between the person and the plane mirror should be ()
A. 1m B. 2m C. 3M D. 4m
∵ the distance between the visual acuity chart and the plane mirror is 3 m, the distance between the image formed by the visual acuity chart and the plane mirror is 3 m, it is known that the distance between the eye and the visual acuity chart should be 5 m, and the distance between the person and the plane mirror should be 5 M-3 M = 2 m
A person with a height of 1.8m stands at 3M of the plane mirror. At this time, the distance between him and his image is m, and the image height is m
The distance between him and his image is 6m
The image height is 1.8m
RELATED INFORMATIONS
- 1. A person of 80 meters stands in front of the plane mirror. The height of his image in the mirror () the distance between people and images () if he walks forward 0.2 meters, the distance between people and images For () Fill in the blanks and explain
- 2. Stack the cuboid building blocks 3 cm long, 2 cm wide and 1 cm high into the smallest cube. The cube edge length is () cm, and at least () blocks are needed
- 3. The edge length of a cube is 5cm, and four such cubes are used to form a large cuboid. The surface area of a large cuboid may be () square centimeter or () square centimeter The edge length of a cube is 5cm. Four cubes are used to form a large cuboid. The surface area of a large cuboid may be () square centimeter or () square centimeter
- 4. The sum of the edges of a cube is 48 cm, and its volume is () cubic cm A. 64 cubic centimeter B. 64 square centimeter C. 64 centimeter
- 5. To cut a cuboid into the largest cube, how long is its edge? It is 12 cm long, 6 cm wide and 8 cm high
- 6. How many square centimetres does the surface area of the cuboid decrease after the cuboid is lined up What's the square percentage? Yes, there will be an extra reward
- 7. The toy factory produced 2500 more children's toys in May than in April, 4 / 5 more. How many children's toys did the toy factory produce in April? Mingzhu power plant burned 24000 tons of coal in October, 1 / 4 less than that in September. How many tons of coal was burned in September?
- 8. A pyramid geometry is composed of several cubes, and the construction method is as shown in the figure. The four vertices of the lower bottom surface of the upper cube are the midpoint of each side of the upper bottom surface of the lower cube. It is known that the edge length of the lowest cube is 2, and the surface area of the pyramid (including the bottom area of the lowest cube) is more than 39, then the number of cubes in the pyramid is at least () A. 4B. 5C. 6D. 7
- 9. Put two cubes of the same size together. Guess how many faces there are now. If you put three cubes together?
- 10. Paint the six sides of a cube shaped building block, and then saw them into 64 small blocks of the same size. How many pieces are there on one side, two sides, three sides and none?
- 11. The solution of the equation a (x + m) &# 178; + B = 0 of X is X1 = - 2, X2 = 1, then the solution of the equation a (x + m + 2) &# 178; + B = 0 is X1 = - 2, X2 = 1
- 12. Calculate (a-b-c) (B + C-A) &# 178; (C-A + b) &# 179; (1) calculation of (a-b-c) &; (B + C-A) &; (C-A + b) &; (C-A + b) &; ⑵(-x)²•(-x)³+2x•(-x)∧4-(-x)•x∧4 ⑶x•x∧(m-1)+x²•x∧(m-2)-3•x³•x∧(m-3)
- 13. [(a + b) &# 178; - (a-b) &# 178; + 6A & # 178; B & # 179;] / (- 2Ab), where a = - 2, B = 1 If the circumference of △ DEF is 15, then the length of BC side is____
- 14. 1. (a-b) &# 178; (a-b) &# 178; (a-b) &# 178; (B-A) &# 178; (B-A) &# 178; (a + b) 178; (a-b) &# 178; (B-A) &# 178; (B-B) &# 178; (B-A) &# 178; (a + B) 178
- 15. A 12.56 decimeter long wire encircles a circle. How many square decimeters is the area of this circle
- 16. An isosceles trapezoid is formed by a 12.4 decimeter long iron wire. It is known that the two sides of the trapezoid are 6.4 decimeters long and the area is 9 square decimeters. What is the height of the trapezoid?
- 17. An isosceles trapezoid is formed by a 12.4 decimeter long iron wire. It is known that the two sides of the trapezoid are 6.4 decimeters long and the area is 9 square decimeters. What is the height of the trapezoid?
- 18. A village plans to build an isosceles trapezoid channel in the east of the village. The cross-section area is 1.6. The width of the upper entrance is 1.6m more than the width of the channel bottom, and the depth of the channel is 0.4m less than the width of the channel bottom
- 19. Known trapezoid area is 36 square meters, the bottom is 3 meters, the bottom is 5 meters, how high is it?
- 20. A village plans to build a canal, its cross section is isosceles trapezoid, the bottom angle is 120 degrees, the sum of the two waist and the bottom is 4 meters. When the depth X of the canal is what, the cross-sectional area s is the largest, what is the maximum area?