question_answer

A and B are two nails on a horizontal line. AC, BC are two uniform strings from which a weight of 100 N is suspended. The tension of AC is: (in N):

A)  100 N                                   

B)  80 N                     

C)  60 N                     

D)         50 N

Correct Answer: B

Solution :

According Lamis theorem \[\frac{{{T}_{1}}}{\sin 180{}^\circ -\theta }=\frac{{{T}_{2}}}{\sin \,(90{}^\circ +\theta )}=\frac{W}{\sin 90{}^\circ }\] \[\sin \theta =\frac{4}{5},\]         \[\cos \theta =\frac{3}{5}\] So,          \[{{T}_{1}}=W\sin \theta =100\times 4\text{/}5=80N\]