question_answer

A block of mass 5 kg is (i) pushed in case and (ii) pulled in case , by a force F = 20 N, making an angle of \[30{}^\text{o}\] with the horizontal, as shown in the figures. The coefficient of friction between the block and floor is \[\mu =0.2.\]The difference between the accelerations of the block, in case and case will be : \[(g=10m{{s}^{-2}})\]

[JEE Main 12-4-2019 Afternoon]

A) \[0m{{s}^{-2}}\]

B) \[0.8\,m{{s}^{-2}}\]

C) \[0.4\,m{{s}^{-2}}\]

D) \[3.2\,m{{s}^{-2}}\]   

Correct Answer: B

Solution :

[b]

\[{{N}_{1}}=60\]                                  \[{{N}_{2}}=40\]

\[{{a}_{1}}=\frac{10\sqrt{3}-0.2\times 60}{5}\]            \[{{a}_{2}}=\frac{10\sqrt{3}-0.2\times 40}{5}\]

\[{{a}_{1}}-{{a}_{2}}=0.8\]