A) 10 m/s
B) 1000 m/s
C) 500 m/s
D) None of these
Correct Answer: B
Solution :
[b] When mirror is rotated with angular speed \[{{N}_{1}}\times \frac{\ell }{4}={{N}_{2}}\times \frac{\ell }{3}\] the reflected ray rotates with angular speed \[2\,\omega =(36\,rad/s)\] sped of spot \[=\left| \frac{dh}{dt} \right|=\left| \frac{d}{dt}(10\,\cot \theta ) \right|=\left| -\,10\,\text{cose}{{\text{c}}^{2}}\theta \,\frac{d\theta }{dt} \right|\] \[=\,\left| -\frac{10}{{{(0.6)}^{2}}}\times 36 \right|=\,1000\,m/s\].You need to login to perform this action.
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