question_answer

A body of weight 50 N placed on a horizontal surface is just moved by a force of 28.2 N. The frictional force and the normal reaction are

A) 10 N, 15 N                    

B) 20 N, 30 N

C) 2 N, 3 N                       

D) 5 N, 6 N

Correct Answer: B

Solution :

\[Frictional\, force,\, =f\,\,=\, 28.2\, cos 45{}^\circ \] \[=\,\,28.2\,\,\times \frac{1}{\sqrt{2}}\,\,=\,\,20\,\,N\] Normal reaction \[\operatorname{R} = 50 -28.2 \,sin\, 45{}^\circ  \,=\, 30 N\]