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 $
