How Fast Will the Climber Accelerate and How Long Until the Rock Falls?

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orange03
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A 75 kg climber finds himself dangling over the edge of an ice cliff, as shown in the figure below. Fortunately, he's roped to a 980 kg rock located 51 m from the edge of the cliff. Assume that the coefficient of kinetic friction between rock and ice is 5.5×10−2. What is his acceleration, and how much time does he have before the rock goes over the edge? Neglect the rope's mass. What is his acceleration? How much time does he have before the rock goes over the edge?

+Ft-Fr=max
+Ft-mg=may

ax=(mg-uk(Mg))/(M-m)
I keep getting ax= 0.228 m/s^2 but that's the answer and I do not know what I am doing wrong. Help please!
 
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Welcome to PF!

Hi orange03! Welcome to PF! :wink:
orange03 said:
ax=(mg-uk(Mg))/(M-m)

Why (M-m)? :smile: