Question 532168
The force needed to pry a nail from a piece of wood varies inversely with the length of the crowbar used to remove the nail.
 If a 6 inch long crowbar requires 15 pounds of force, how many pounds are required by an 18 inch long crowbar?
:
Let f = the force required using an 18'
:
An inverse ratio equation makes this easy.
{{{6/18}}} = {{{f/15}}}
cross multiply
18f = 6 * 15
18f = 90
f = 90/18
f = 5 lb of force for an 18"