question_answer

                A block of mass 1 kg is placed on a truck which accelerates with acceleration \[5\,m/{{s}^{2}}\]. The coefficient of static friction between the block and truck is 0.6. The frictional force acting on the block is:     

A)                 5 N                        

B)                 6 N        

C)                 5.88 N

D)                 4.6 N

Correct Answer: B

Solution :

                          The frictional force acting on the block                                 \[f=\mu R\]                 but from figure, R = mg                         \[\therefore f=\mu mg\]                 Here, \[\mu =0.6,\,\,m=1\,\,kg,\,g=10\,m/{{s}^{2}}\]                         \[\therefore f=0.6\times 1\times 10=6\,N\]                 Note:    Due to acceleration of truck, the block experiences a forward force                 \[F=ma\]                 Since \[f>F\], so block is not displaced from its previous position.