Answer:
Step-by-step explanation:
Given
Light makes [tex]N=9\ rpm[/tex]
Light makes [tex]\frac{\mathrm{d} \theta }{\mathrm{d} t}=\dfrac{2\pi N}{60}=0.3\pi rad/s[/tex]
From figure
[tex]\tan \theta =\dfrac{x}{5}[/tex]
differentiate w.r.t time we get
[tex]\sec ^2\theta\times \frac{\mathrm{d} \theta }{\mathrm{d} t}=\dfrac{1}{5}\times \frac{\mathrm{d} x}{\mathrm{d} t}[/tex]
[tex]at\ x=1[/tex] [tex]\sec \theta =\dfrac{26}{25}[/tex]
[tex]\dfrac{26}{25}\times (0.3\pi )=\dfrac{1}{5}\times \frac{\mathrm{d} x}{\mathrm{d} t}[/tex]
[tex]\frac{\mathrm{d} x}{\mathrm{d} t}=4.90\ km/s\approx 294\ km/min[/tex]
