Engineering Mechanics - DynamicsChapter 15Problem 15-31The log has mass Mand rests on the ground for which the coefficients of static and kineticfriction are μsand krespectively. The winch delivers a horizontal towing force Tto its cable at Awhich varies as shown in the graph. Determine the speed of the log when t= t2. Originally thetension in the cable is zero. Hint:First determine the force needed to begin moving the log.Given:M500 kg=t13s=s0.5=T11800 N=k0.4=g9.81ms2=t25s=Solution:To begin motion we need2T1t02t12⎛⎜⎝⎞⎟⎠sMg=t0s2T1t1=t02.48 s=Impulse - Momentum0t0t1t2T1tt1⎛⎝⎞⎠2⌠⎮⎮⎮⌡d+2T1t2t1−()+kMg t2t0−−Mv2=v21Mt0t1t2T1tt1⎛⎝⎞⎠2⌠⎮⎮⎮⌡d2T1t2t1−+k2t0−−⎡⎢⎢⎢⎣⎤⎥⎥⎥⎦=v27.65
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