Q. A cart of mass $M$ has a block of mass $m$ in contact with it as shown in the figure-2.133. The coefficient of friction between the block and the cart is $\mu$. What is the minimum acceleration of the cart so that the block $m$ does not fall ?

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A

$\mu g$

B

$g / \mu$

C

$\mu / g$

D

$M \mu g / m$

Solution:

$N=m a$
To prevent block $m$ from falling,
$\mu N >m g $
$ \mu m a >m g $
$ a >\frac{g}{\mu} $

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