Answer:
D = [tex]\sqrt{\frac{216W}{35L} }[/tex]
Step-by-step explanation:
From the given question, the expression showing the relationship among the weight, length and diameter of the metal bar is;
W [tex]\alpha[/tex] L[tex]D^{2}[/tex]
W = kL[tex]D^{2}[/tex]
where k is the constant of proportionality.
When W = 140, D = 4 and L = 54, then;
140 = k(54)[tex](4)^{2}[/tex]
= 864k
k = [tex]\frac{140}{864}[/tex]
= [tex]\frac{35}{216}[/tex]
k = [tex]\frac{35}{216}[/tex]
⇒ W = [tex]\frac{35LD^{2} }{216}[/tex]
So that;
35L[tex]D^{2}[/tex] = 216W
[tex]D^{2}[/tex] = [tex]\frac{216W}{35L}[/tex]
D = [tex]\sqrt{\frac{216W}{35L} }[/tex]
