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  • A body of mass m=10−2 kg is moving in a medium and experiences a frictional force  Its initial speed is <img alt="v_{0}= 10ms^{-1}" src="

A body of mass m=10−2 kg is moving in a medium and experiences a frictional forceF= -kv^{2}  Its initial speed is v_{0}= 10ms^{-1}.  If, after 10 s, its energy is \frac{1}{8}  mv{_{0}}^{2}  the value of k will be :  
Option: 1 10−3 kg m−1  
Option: 2  10−3 kg s−1  
Option: 3  10−4 kg m−1  
Option: 4 10−1 kg m−1 s−1  
 

Answers (1)

best_answer

As we learnt in 

\frac{1}{2}mv{_{f}}^{2}=\frac{1}{8}mv{_{o}}^{2}

v_{f}=\frac{Vo}{2}=5 m \slash s

\left ( 10^{-2} \right )\frac{dv}{dt}=-KV^{2}

\int_{10}^{5}=-100k\int_{0}^{10}dt\Rightarrow \frac{1}{5}-\frac{1}{10}=100 k (1^{\circ})

K=10^{-4}

Posted by

vishal kumar

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