InterviewSolution
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InterviewSolution
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A plank with a box on it at one end is gradully raised about the other end. As the angle of inclination with the horizntal reaches `30^(@)` , the box starts to slip and slide `4.0m` down the plank in `4.0s` . The coefficients of static and knitic friction between the box and the plank will be, respectively. A. 0.4 and 0.3B. 0.6 and 0.6C. 0.6 and 0.5D. 0.5 and 0.6 |
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Answer» Correct Answer - C `mu_(s)=tan30^(@)=(1)/(sqrt(3))=0.57~~0.6` `S=ut+(1)/(2)at^(2)` `4=0+(1)/(2)(gsin30^(@)-mu_(k)cos30^(@))(4)^(2)` `0.5=10xx(1)/(2)-mu_(k)10xx(sqrt(3))/(2)` `5sqrt(3)mu_(k)=4.5` `mu_(k)=0.51` |
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