# Depression of a Diving Board

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1. Oct 8, 2009

### haroldtreen

1. The problem statement, all variables and given/known data

A diving board has a vertical depression of 15cm when a 60kg person stands on it 3m from the fulcrum.

If another person was to stand on the same diving board, 2m from the fulcrum, how much would they have to weight to create 4cm of depression?

In class we did 2 experiments:

1st - Find out the relationship between depression and weight. Noted the depression of a ruler when numerous weights were suspended from it, plotted the data and got the straight line equation:
y = 1.35x - 1.3

2nd - Looked at how the depression changed in relation to the length of the ruler when 1kg was suspended from the tip. Got a power graph that using logs turned into a straight line graph as well:
log(y) = 2.5*log(mass) - 3.87

2. Relevant equations
y = 1.35x - 1.3
log(y) = 2.5*log(mass) - 3.87

3. The attempt at a solution

d= depression
m= mass
K = constant
n = exponent of power equation
L= length of board

K=?
d=15cm
m= 60kg
n= 2.5
L= 300cm

d=KmL^n

(15cm)/(60kg)(300cm)^2.5 = K

Then since I had K, I could input the second set of values and find out m... didn't work though :(.

Would love some help!
Thanks a bagillion! :D
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Oct 9, 2009

### tiny-tim

Welcome to PF!

Hi haroldtreen! Welcome to PF!

Why are you using the 2nd equation? That was for the fulcrum moving nearer the tip.