A) \[\sqrt{\frac{2}{5}}T\]
B) \[\sqrt{\frac{5}{2}}T\]
C) \[\frac{\sqrt{5}T}{2}\]
D) \[\frac{2T}{\sqrt{5}}\]
Correct Answer: D
Solution :
When the lift is moving upwards, then from Newtons second law of motion, net force on him is \[F=ma\] \[F=-ma\] Therefore, \[-ma=mg-R\] \[R=mg+ma\] \[R=m(g+a)\] Time period \[T=2\pi \sqrt{\frac{l}{g}}\] \[T=2\pi \sqrt{\frac{l}{g+a}}\] When lift is stationary, time period is \[T=2\pi \sqrt{\frac{l}{g}}\] Also\[g=g+a=g+g/4=\frac{5g}{4}\] \[\frac{T}{T}=\frac{\sqrt{5/4g}}{g}=\frac{\sqrt{5}}{2}\] \[T=\frac{2}{\sqrt{5}}T\]
You need to login to perform this action.
You will be redirected in
3 sec
