A) \[2\,\,s\]
B) \[4\,\,s\]
C) \[8\,\,s\]
D) \[10\,\,s\]
Correct Answer: B
Solution :
When a body is revolving in circular motion it is acted upon by a centripetal force directed towards the centre. Water will not fall if weight is balanced by centripetal force. Therefore, \[mg=\frac{m{{v}^{2}}}{r}\] \[\Rightarrow \] \[{{v}^{2}}=rg\] ... (i) Circumference of a circle is\[2\pi r\]. Time for a revolution\[=\frac{2\pi r}{r}\] Putting the value of v from Eq. (i), we get \[T=\frac{2\pi r}{\sqrt{gr}}=2\pi \sqrt{\frac{r}{g}}\] Given,\[r=4\,\,m,\,\,g=9.8\,\,m/{{s}^{2}}\] \[\therefore \] \[T=2\pi \sqrt{\frac{4}{9.8}}=T=\frac{4\pi }{\sqrt{9.8}}=4s\]You need to login to perform this action.
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