A person is 1.9 m tall. Where should he place the top of a mirror on the wall so he can see the top of his head? Assume his eyes are 5.4 cm below the top of his head. Find a minimal vertical distance from the level of the person's eyes to the top of the mirror.

Question

Physics

Delaney Gilmore

28 December, 06:40

A person is 1.9 m tall. Where should he place the top of a mirror on the wall so he can see the top of his head? Assume his eyes are 5.4 cm below the top of his head. Find a minimal vertical distance from the level of the person's eyes to the top of the mirror.

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Answers (1)

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Nia Maynard · Answer 1

Answer: a) 1.846m

b) 0.923m

Explanation: given that height h = 1.9m

Assume his eyes are 5.4 cm below the top of his head

5.4 cm = 5.4 / 100 = 0.054 m

1.9 - 0.054 = 1.846 meter

The top of the mirror should be placed at 1.846m

That is the vertical distance from his eyes to top of his head.

Light must travel from the top of his head to the mirror in order for him to see the head. Then travel from this position to his eyes. To do this, the mirror must be placed at a position that is halfway between his eyes and the top of his head.

The minimal vertical distance from the level of the person's eyes to the top of the mirror will be:

d = ½ * 1.846 = 0.923 meters