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phy131studiof15:lectures:m1p1sol [2015/09/30 17:22] mdawber [Question 1 Solution] |
phy131studiof15:lectures:m1p1sol [2015/09/30 17:23] mdawber [Question 1 Solution] |
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For parts C-G consider a case where $m_{1}=$4 kg and $m_{2}$=1 kg, $\mu_{s}$=0.2 and $\mu_{k}$=0.15. | For parts C-G consider a case where $m_{1}=$4 kg and $m_{2}$=1 kg, $\mu_{s}$=0.2 and $\mu_{k}$=0.15. | ||

- | C. (5 points) If $\theta=30^{o}$ what is the velocity and displacement of $m_{1}$, 0.5\,s after the system has been released from rest? | + | C. (5 points) If $\theta=30^{o}$ what is the velocity and displacement of $m_{1}$, 0.5s after the system has been released from rest? |

$a=\frac{4+1\sin 30^{o}-0.15\cos30^{o}}{4+1}\times9.8=8.57\mathrm{ ms^{-2}}$ | $a=\frac{4+1\sin 30^{o}-0.15\cos30^{o}}{4+1}\times9.8=8.57\mathrm{ ms^{-2}}$ | ||

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F. (5 points) How much work is done by friction during the motion in part (C)? | F. (5 points) How much work is done by friction during the motion in part (C)? | ||

- | $W_{Fr}=-\mu_{k}m_{2}g\cos\theta d=-0.15\times 1 \times 9.8\times\cos30^{o}\times 1.07=1.36\mathrm{J}$ | + | $W_{Fr}=-\mu_{k}m_{2}g\cos\theta d=-0.15\times 1 \times 9.8\times\cos30^{o}\times 1.07=-1.36\mathrm{J}$ |

G. (5 points) How much work is done by the normal force on $m_{2}$ during the motion in part (C) ? | G. (5 points) How much work is done by the normal force on $m_{2}$ during the motion in part (C) ? |