Q. The coefficient of friction between $4 \,kg$ and $5 \,kg$ blocks is $0.2$ and between $5 \, kg$ block and ground is $0.1$ respectively. Choose the correct statements: (Take $g=10 m / s ^{2}$ )

Laws of Motion Report Error

A

Minimum force needed to cause system to move is $17 \, N$

14%

B

When force is $4 N$ static friction at all surfaces is $4\, N$ to keep system at rest

29%

C

Maximum acceleration of $4 kg$ block is $2 \, m / s ^{2}$

39%

D

Slipping between $4 \, kg$ and $5 \, kg$ blocks start when $F$ is $17\, N$

18%

Solution:

$f_{1 \max } =0.2 \times 40$
$=8 \,N$
Maximum acceleration of $4\, kg$ block
$=\frac{f_{1 \max }}{4 k g}$
$=2 \,m / s ^{2}$

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