Question

A block of mass 2kg is resting over another block of mass 6 kg. 2kg is connected to one end of a string fixed to a vertical wall as shown. If the coefficient of friction between the blocks is 0.4, the force required to pull out the 6kg block with an acceleration of 1.5 m/s${}^2$ will be (g=10 ms${}^{-2}$)

• A. 17 N
• B. 9 N
• C. 8 N
• D. 1 N

Answer 1

The correct option is A 17 N

${\left(f_s\right)}_{max}=\mu \times 2\times g=0.4\times 2\times 10=8NF-{\left(f_s\right)}_{max}=maF-8=6\times 1.5F=17N$