question_answer

A mass of 10 kg is suspended from a spring balance. It is pulled aside by a horizontal string so that it makes an angle of \[60{}^\circ \]with the vertical. The new reading of the balance is

A)  20 kg-wt       

B)  10 kg-wt

C)  10\[\sqrt{3}\]kg-wt

D)  20\[\sqrt{3}\] kg-wt

Correct Answer: A

Solution :

The situation is shown in figure At an angle of \[60{}^\circ \],                 \[T\cos \theta =mg\] \[T=\frac{mg}{\cos \theta }=\frac{10g}{\cos {{60}^{o}}}\] \[=\frac{10}{1/2}kg-qt\] \[=20kg-wt\]