Q. On the horizontal surface of a truck, a block of mass $1 \,kg$ is placed $(\mu=0.6)$ and truck is moving with acceleration $5\, m / s ^{2}$. The frictional force acting on the block will be: $\left(g=10\, m / s ^{2}\right)$
Jharkhand CECEJharkhand CECE 2003
Solution:
The frictional force acting on the block
$ f=\mu R $
but from figure, $ R=mg $
$ f=\mu \,m\,g $
Here, $ \mu =0.6,\,m=1\,kg,\,g=10\,m/s^{2} $
$ \therefore $ $ f=0.6\times 1\times 10\,=6\,N $
Due to acceleration of truck, the block experiences a forward force
$ F=ma=1\times 5=5\,N $
Since $ f>F, $
so block is not displaced from its previous position.
