Physics
posted by Soph on .
A man places a torche on the ground, 10m away from a wall. He sees a shade on the wall and gets a friend to measure the height of the shadow as he walks towards the wall. Here are the results:
Distance from torch to man height of shadow
1 20
2 10
3 6.7
4 5
5 4
6 3.3
7 2.9
8 2.5
find the height of the man

Lets denote x = the height of the man, h = the height of the shadow (the right column of data), and y = the distance from torch to the man (the left column of data), then you can write a proportion: x/y = h/10 or x = y*h/10. Use any pair of given data now to find x: the first => 1*20/10 = 2; the second => 2*10/10 = 2, and so on. Finally, x =2.