The force, f, between two magnets is inversely proportional to the square of the distance x between them. when x=3 f=4. How do you find an expression for f in terms of x and calculate f when x=2?

1 Answer
Jan 30, 2017

f=36/x^2

f=9

Explanation:

Break down the question into sections

The basic relationship as stated

" (1) The force" f " between two magnets" is
"inversely proportional to the square of the distance "x"

=>f" "alpha" "1/x^2

" change to an eqn."

=>f=k/x^2" where " k " is the constant of proportionality"#

find the constant of proportionality

" (2) when " x=3, f=4.

4=k/3^2

=>k=36

:.f=36/x^2

Now calculate f given the x value

" (3) " x=2

f=36/2^2=36/4=9