Question

A block of mass $1\text{kg}$ lies on a horizontal surface in a truck. The coefficient of static friction between the block and the surface is $0.6$. If the acceleration of the truck is $5{\text{m/s}}^2$, the frictional force acting on the block is,
[Take $g=10{\text{m/s}}^2$]

• A. $6\text{N}$
• B. $10\text{N}$
• C. $15\text{N}$
• D. $5\text{N}$

Answer 1

The correct option is D $5\text{N}$

Pseudo force method:

Here, $N=mg=1\times 10=10\text{N}$
$\Rightarrow f_{s_{max}}=\mu \times N=0.6\times 10=6\text{N}$

Now, $F_{pseudo}=ma=1\times 5=5\text{N}$

$\text{As,}{F}_{pseudo}<f_{s_{max}}$

$\therefore$The required frictional force is of $5\text{N}$ magnitude.

Hence, $\left(A\right)$ is the correct answer.