find the least value of P required to cause the system of blocks as shown in the figure have impending motion to the left. The coefficient of friction under each block is 0.20

Question

isabel☺ · Answer

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anonymous · Answer

First calculate what would be the acceleration of the system if there was no P.. using free body diagram for each block

once you know the acceleration, you can find what should be the force that you should put in the opposite direction to stop it from moving!

isabel☺ · Answer

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anonymous · Answer

T+f1??

anonymous · Answer

and why would the acceleration be that way? :O

isabel☺ · Answer

if i neglect P there would be no friction?

anonymous · Answer

there is friction.. 
but you got the acceleration direction for the first body wrong... think logically
if you left the whole system.. would it go towards the left or towards the right?? it would accelerate towards the right!? isn't it? 

so the friction would be in the opposite direction!

isabel☺ · Answer

is 30 kN weight?

isabel☺ · Answer

so it's weight

anonymous · Answer

yea it is the weight.. ! cause weight is basically force and force has unit of N.. mass is KG!

isabel☺ · Answer

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is my fbd correct?