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?

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Answer 1 · 2017-01-30T13:24:28

#f=36/x^2#

#f=9#

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#