The minutes hand of a clock length is 10.5 cm. Then area swept by it in 10 minutes is ……… cm^2.
The minutes hand of a clock length is 10.5 cm. Then area swept by it in 10 minutes is ……… cm2.
(A) 115.5
(B) 57.75
(C) 11.55
(D) 575.5
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Correct option is: (B) 57.75
The length of the minute hand of a clock is r = 10.5cm.
\(\because\) Area swept by minute hand in 1 hour (60 minutes).
= \(\pi r^2 \, cm^2\)
\(\therefore\) Area swept by minute hand in 10 minutes = \(\frac {\pi r^2}{60} \times 10 cm^2\)
= \(\frac {\pi r^2}{6} = \frac 16 \times \frac {22}7 \) x 10.5 x 10.5 = 11 x 0.5 x 10.5.
= \(57.75 \, cm^2\).
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