Question

the load L that a helical spring can suport varies directly as the cube of its wire diameter d and inversal as its coil diameter D. a spring for which d=0.1cm and D=0.9cm can suport 50N. what is the coil diameter of a similar spring that supports 78.5N and for which d=0.2cm?

Answer 1

First write the equation from the first sentence:

L=kd^3/D

Answer 2

Now replace d with .1, replace D with .9, replace L with 50 and find k

Answer 3

Now rewrite the original equation replacing k with the value you just found.

Answer 4

Then replace L with 78.5, replace d with .2 and solve for D

Answer 5

yes i am doing it

Answer 6

did you get 500 for k

Answer 7

I didn't do it yet. Hold on

Answer 8

No. i will show you

Answer 9

\[50=\frac{k(.1)^{3}{.9}}\]