Consider the situation shown in the figure. The horizontal surface below the bigger block is smooth. The coefficient of friction between the blocks is u. Find the minimum and the maximum force that can be applied in order to keep the smaller blocks at rest with respect to bigger block.

Question

anonymous · Answer

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vincent-lyon.fr · Answer

You can use non-inertial frame here.
Do not forget to carefully choose the system you are using to write N's laws.

anonymous · Answer

I have found the minimum force. need to find maximum.

anonymous · Answer

Maximum force will be when the friction starts acting opposite to the previous direction. The hanging block will start going up

vincent-lyon.fr · Answer

Maybe there is no maximum force. (I have not done the problem yet).

rajat97 · Answer

do we know the mass of the bigger block?

rajat97 · Answer

okay

rajat97 · Answer

it would be very easy if the mass of the bigger block were given

anonymous · Answer

In fact there is no use of mass of bigger block

rajat97 · Answer

why???
if you need to find the acceleration of the whole system, you need the mass of the bigger block

anonymous · Answer

This question is from hc verma vol. 1 page no. 94 example no. 9

anonymous · Answer

okk , you are right. lol I forgot we need to find acc. let that be M

rajat97 · Answer

yeah

rajat97 · Answer

as Mr. Vincent said , you can use the concept of non-inertial reference frame
and newton's 2nd law equation
i'll post what i did

rajat97 · Answer

let the mass of the bigger block beM
so the total acceleration of the whole system = $$F/2m+M$$
so if we see the smaller blocks w.r.t the bigger block, we shall apply the pseudo force in opposite direction of the motion of the system so the pseudo force on the upper block will be in the direction of friction and the pseudo force on the lower block will increase the normal foce that is acting on the bigger block 
it will look like this:

rajat97 · Answer

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