(11%) Problem 5: A contestant in a winter sporting event pulls a 44 kg block of
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(11%) Problem 5: A contestant in a winter sporting event pulls a 44 kg block of ice in the positive horizontal direction with a rope over his shoulders across a frozen lake as shown in the figure. Assume the coefficients of static and kinetic friction are ,-0.1 andHy-0.03 25° Otheexpertta.com 50% Part (a) Calculate the minimum force F he must exert to get the block sliding in newtons. Grade Summary Deductions Potential min 15 2% 98% sin) tan( 7 89 HOME coso asino Attempts remaining: (2% per attempt) detailed view cotan() acoso atan) acotan sinh) 2% tanh cotanh( END Degrees Radians BACKSPACE DL Hints: 3% deduction per hint. Hints remaining:- Feedback: 0% deduction per feedback. 50% Part (b) What is its acceleration in my? once it starts to move, if that force is maintained?Explanation / Answer
in vertical,
Fnet = N + Fsin25 - m g = 0
and f_max = us N
to start it move, Fcos25 - f_max= 0
F cos25 - 0.1 m g + 0.1 F sin25 = 0
F = (0.1 x 44 x 9.81) / (cos25 + 0.1 sin35)
F = 45.5 N ........Ans
(B) once it starts moving then kinetic friction will act.
fk = uk N = 0.03 ( 44x9.81 - 45.5sin25) = 12.37 N
Fnet = 45.5 cos25 - 12.37 = 44 a
a = 0.656 m/s^2
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