Question

F

is inversely proportional to
d
2
.
When
F
=
6
,
d
=
6

Work out
F
when
d
=
3

Answer 1

F = 24

Explanation:

Given that F is inversely proportional to d² then the equation relating them is

F=
`(k)/(d^2)` ← k is the constant of proportion

To find k use the condition F = 6 when d = 6 , then

6 =
`(k)/(6^2)` =
`(k)/(36)` ( multiply both sides by 36 )

216 = k

F =
`(216)/(d^2)` ← equation of proportion

When d = 3 , then

F =
`(216)/(3^2)` =
`(216)/(9)` = 24

Answer 2

Explanation:

P varies to d²

F=K/d²

where K is the constant

6=k/6²

6=k/36

K= 216

we write the equation

F=k/d²

we substitute

F=216/3²

F=216/9

F= 24