Question

M is directly proportional to r2 When r=2, m=14 Work out the value of m when r=12

Answer 1

we have M is durectly porpotional to r^2

so M=(k)r^2

and when r=2, m=14

so 14=(k)(2)^2

k=14/4 =7/2

so when r=12

m= (7/2)(12)^2 =(7/2)(144) = 504