1.

:) The ratio of angular speed of a second-hand to the hour - hand of a watchesa) 60: 1b) 72: 1c) 720:1d) 3600:1​

Answer»

\huge\underline{\underline{\bf \orange{Question-}}}

The RATIO of angular speed of a second-hand to the hour - hand of a watches.

\huge\underline{\underline{\bf \orange{Solution-}}}

We know that ,

In watch's second hand it takes 1 min (60s) to COMPLETE one Angular distance i.e 2π

So ,

\implies{\sf Angular\:Speed(\omega_1)=\dfrac{2π}{60}}

\implies{\sf \pink{ \omega_1 = \dfrac{π}{30}\:rad/s}}

And ,

Hour hand to watch take 12 HOURS (12×3600=43200s) to complete one rotation i.e 2π

\implies{\sf Angular\:Speed(\omega_2)=\dfrac{2π}{43200} }

\implies{\sf \pink{\omega_2= \dfrac{π}{21600} \:rad/s}}

\large{\rm Ratio \: of \: second-hand \: and \:hour-hand }

\implies{\sf \dfrac{\omega_1}{\omega_2}=\dfrac{π/30}{π/21600} }

\implies{\sf \dfrac{\omega_1}{\omega_2}=\dfrac{<klux>720</klux>}{1}}

\implies{\bf \red{\omega_1:\omega_2=720:1} }

\huge\underline{\underline{\bf \orange{Answer-}}}

Option (c) 720 : 1

Ratio of angular speed of a second-hand to the hour - hand of a watches is {\bf \red{720:1}}.



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