M is directionly proptional to r squared when r=2, m=14

A)work out the value of m when r is 12

b) work out the value or r when m is 224

9514 1404 393

  A) 504

  B) 8

Step-by-step explanation:

The statement of proportionality can be written as the equation ...

  m = kr²

Then we can find k from ...

  k = m/r² = 14/2² = 7/2

That is, ...

  m = (7/2)r²

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Using this relation, we can find m for r=12:

  m = (7/2)·12² = 7·72

  m = 504 . . . for r = 12

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And, we can use the same equation to solve for r when m=224.

  224 = 7/2·r²

  r² = 64

  r = √64

  r = 8 . . . for m = 224