# Diagram of the see-saw and parallel mirrors

• ritwik06
In summary, two parallel mirrors on a sea-saw can reflect a beam of light at an angle determined by the angle of the sea-saw. In the second problem, the statement |A+B|=|A-B| asks for the meaning of the magnitude of the vector sum being equal to the magnitude of the vector difference. This is only possible if the two vectors are perpendicular to each other.
ritwik06
1. Two mirrors are placed parallel to each other on a sea-saw. A beam incident in analmost vertical plane, on the first mirror is reflected to be incident on the second and then is further reflected to form a spot on the wall at some distance away. If the sea-saw is turned through an angle theta, through what angle will the reflected beam turn?

2. If for two vectors A and B; |A+B|=|A-B| then

a) |A-B|=|A|+|B|
b) |A+B|=|A|-|B|
c) |A+B|=0
d) |A.B|=0

Please let me explai, I have no idea about these questions. Please explain it to me. I have astonomy olympiad so I got them by reading the past papers.

In the first problem, it would be useful to draw a diagram of the see-saw and parallel mirrors.

In the second problem |A| means magnitude of vector A.

The problem asks for the meaning of the statement 'the magnitude of the vector sum of vectors A and B = magnitude of the vector difference of A and B. How is this possible? What other condition is inferred?

Astronuc said:
In the first problem, it would be useful to draw a diagram of the see-saw and parallel mirrors.

In the second problem |A| means magnitude of vector A.

The problem asks for the meaning of the statement 'the magnitude of the vector sum of vectors A and B = magnitude of the vector difference of A and B. How is this possible? What other condition is inferred?

Please sir, try to be clear. I can't grasp things of that level like that. I am just at the 9th standard (14 yrs. old)

ritwik06 said:
Please sir, try to be clear. I can't grasp things of that level like that. I am just at the 9th standard (14 yrs. old)
Take a piece of paper and draw two vectors A and B such that the sum of the two vectors A + B has the same length as the difference between the vectors A - B. Which of the four answer conditions is statisfied by these two vectos?

## 1. How does a see-saw work?

A see-saw is a simple machine that consists of a long plank of wood or metal supported by a fulcrum in the middle. When one end of the plank goes down, the other end goes up due to the law of lever. This creates a back-and-forth motion, allowing two people to play on the see-saw.

## 2. What is the purpose of a parallel mirror?

A parallel mirror is used to create an optical illusion of infinite reflections. When two mirrors are placed parallel to each other, the reflection of a reflection creates the illusion of a never-ending series of images. This is also known as the "infinity mirror" effect.

## 3. How is a diagram of a see-saw and parallel mirrors drawn?

A diagram of a see-saw and parallel mirrors can be drawn by first sketching a see-saw with a fulcrum in the middle and two people sitting on either end. Then, draw two parallel lines on either side of the see-saw to represent the mirrors. Finally, add in the reflections of the people on the see-saw in the mirrors.

## 4. What is the scientific explanation behind the parallel mirror illusion?

The parallel mirror illusion is created due to the reflection of light. When light hits a mirror, it bounces off at an equal angle to its incident angle. This creates the illusion of a never-ending series of reflections when two mirrors are placed parallel to each other.

## 5. How can the see-saw and parallel mirrors be used in a science experiment?

The see-saw and parallel mirrors can be used in a science experiment to demonstrate the principles of levers and optics. By adding weights or adjusting the position of the mirrors, students can observe how it affects the balance of the see-saw and the number of reflections in the mirrors. This can also be used to discuss concepts such as center of mass and angles of reflection.

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