Laws Of Motion Question 404

Question: Two blocks (m and M) are arranged as shown in Fig. 21. If there is friction between ground and M only and other surfaces are frictionless. The coefficient of friction between ground and M is $ \mu =0.75 $ . The maximum ratio of m and M (m/M) so that the system remains at rest is

Options:

A) $ 1/4 $

B) 3

C) $ 1/3 $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

As sphere is at rest,

$ T=mg $

$ f=T $

and $ f\le \mu N $

Here $ N=Mg+T=( M+m )g $

$ T\le m( M+m )g $

$ mg\le \mu ( M+m )g $

$ \frac{m}{M}\le \frac{\mu }{( 1-\mu)} $

$ \frac{m}{M}\le \frac{0.75}{( 1-0.75 )}\Rightarrow \frac{m}{M}\le 3 $



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