JIPMER Jipmer Medical Solved Paper-2004

  • question_answer
    A particle moves from position \[\overset{\to }{\mathop{{{\mathbf{r}}_{\mathbf{1}}}=3\mathbf{\hat{i}}}}\,+2\mathbf{\hat{j}}-6\mathbf{\hat{k}}\]to  position \[\overset{\to }{\mathop{{{\mathbf{r}}_{2}}=14\mathbf{\hat{i}}}}\,+13\mathbf{\hat{j}}+9\mathbf{\hat{k}}\] under action of force\[\overset{\to }{\mathop{{{\mathbf{F}}_{2}}=4\mathbf{\hat{i}}}}\,+\mathbf{\hat{j}}+3\mathbf{\hat{k}}\,\text{N}\text{.}\]The work done will be:

    A)  100 J                                    

    B)  50 J  

    C)  200 J                    

    D)         75 J

    Correct Answer: A

    Solution :

    Using the formula for work done \[W=\overrightarrow{F}\cdot \overrightarrow{r}=\overrightarrow{F}\cdot (\overrightarrow{{{r}_{2}}}-\overrightarrow{{{r}_{1}}})\] \[W=(4\hat{i}+\hat{j}+3\hat{k})\cdot (14\hat{i}+13\hat{j}+9\hat{k}-3\hat{i}-2\hat{j}+6\hat{k})\] \[W=(4\hat{i}+\hat{j}+3\hat{k})\cdot (11\hat{i}+11\hat{j}+15\hat{k})\] \[W=44+11+45=100\,joule\]


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