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One gets less hurt when one jumps from a height on sand than on hand floor. Why ?

Answer» <html><body><p></p>Solution :When a man jumps on any surface, the surface in contact with the man gets a <a href="https://interviewquestions.tuteehub.com/tag/little-1075899" style="font-weight:bold;" target="_blank" title="Click to know more about LITTLE">LITTLE</a> depressed. This depression is more in the case of a sandy surface than of a hand floor. The initial potential energy of the man is the same in both cases. So the kinetic energy just before <a href="https://interviewquestions.tuteehub.com/tag/hitting-2711575" style="font-weight:bold;" target="_blank" title="Click to know more about HITTING">HITTING</a> the ground is also the same. <br/> Suppose , the mass of the man = m and he jumps from a height h. The average reaction force of the ground on him is <a href="https://interviewquestions.tuteehub.com/tag/r-611811" style="font-weight:bold;" target="_blank" title="Click to know more about R">R</a>. He stops after depressing the ground by x. so his kinetic energy is used up in <a href="https://interviewquestions.tuteehub.com/tag/work-20377" style="font-weight:bold;" target="_blank" title="Click to know more about WORK">WORK</a> done against the <a href="https://interviewquestions.tuteehub.com/tag/net-5194" style="font-weight:bold;" target="_blank" title="Click to know more about NET">NET</a> reaction force R-mg. As kinetic energy just before hitting the ground = potential energy at height = h =mgh , <br/> `(R -mg )x =mghor, R =(1+ h/x) mg` <br/> As x is more for a sandy surface , R is less and hence, the man is less hurt.</body></html>


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