Question

A block of mass $2kg$ is placed on the floor. The coefficient of static friction is $0.4$. If a force of $2.8N$ is applied on the block parallel to floor, the force of friction between the block and floor
(Taking $g=10m{s}^{-2}$ ) is

• A. 2.8 N
• B. 8 N
• C. 2 N
• D. zero

Answer 1

Answer: (A)

Minimum force required to move the block
$=\mu R=\mu mg=0.4\times 2\times 10=8N$
Since the force applied is only $2.8N$, the block fails to move and static fraction $=$ applied force $=2.8N$