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A block of mass m is pushed momentarily along a horizontal surfacewith an initial velocity u. If mu_kis the coefficient of kinetic friction between the object and surface, find the time at which the block comes to rest.

Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :<img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/FM_PHY_XI_V01_C03_SLV_032_S01.png" width="80%"/> <br/>When the block slides, the force acting on the block is kinetic friction which is equal to `f_k = mu_s <a href="https://interviewquestions.tuteehub.com/tag/mg-1095425" style="font-weight:bold;" target="_blank" title="Click to know more about MG">MG</a>`. <br/>From Newton.s second law ma= `-mu_s mg `<br/>The <a href="https://interviewquestions.tuteehub.com/tag/negative-570381" style="font-weight:bold;" target="_blank" title="Click to know more about NEGATIVE">NEGATIVE</a> sign implies that force <a href="https://interviewquestions.tuteehub.com/tag/acts-848461" style="font-weight:bold;" target="_blank" title="Click to know more about ACTS">ACTS</a> on the opposite direction of motion. The acceleration of the block while sliding ` a= - mu_s <a href="https://interviewquestions.tuteehub.com/tag/g-1003017" style="font-weight:bold;" target="_blank" title="Click to know more about G">G</a>` <br/>The negative sign implies that the acceleration is in opposite direction of the velocity. Note that the acceleration depends only on g and the coefficient of kinetic friction We can apply the following kinematic equation <br/> v=u + at<br/>The final velocity is zero. <br/> `t = (u)/(mu_k g)`</body></html>


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