A) a + b
B) 9b - 9a
C) 5b - 4a
D) 4a - 5b
Correct Answer: C
Solution :
From Hookes law, restoring force F is \[F=kl\] where k is spring constant. When L is original length of spring, and k the spring constant, then \[L+\left( \frac{5}{R} \right)=b\] Also, \[L+\left( \frac{4}{k} \right)=a\] \[\therefore \] \[\frac{5}{k}-\frac{4}{k}=b-a\] \[\Rightarrow \] \[k=\frac{1}{b-a}\] \[\therefore \] \[L=b-\frac{5}{k}\] \[\Rightarrow \] \[L=b-5(b-a)=5a-4b\] When tension is 9 N. Length of spring\[=L+\frac{9}{K}\] Length of spring \[=(5a-4b)+9(b-a)\] Length of spring\[=5b-4a\]You need to login to perform this action.
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