- #1
Carbon123
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Homework Statement
A plane mirror of length 20 cm is put up in a wall.The upper part of the mirror is 130 cm above the ground.A person is standing 1 m in front of the mirror.The person's eye is 130 cm from the ground.Suddenly,the mirror falls.How long is the person able to see the tip of his feet ?
Assume that g=10 m/s2
Homework Equations
S=Vot +1/2 at2
Laws of Reflection
V=Vo+at
The Attempt at a Solution
I think that the first time the person sees his feet would be when the lower side of the mirror is at height 65 cm from the ground.Therefore,I used S=Vot+1/2 gt2 and found that it takes 3 s to be at 65 cm from the ground.From then on ,the person would be able to see his feet,so the time can be calculated from S = Vot+1/2gt2 with s being the length of mirror ,the speed is Vo=g.3 and using quadratics the solution is 0.06 s .Please help me out plase check my work,I also do not know if the distance of the person from the mirror matters.
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