Length of a minute hand of a clock is 14 cms. Area swept bv the minute hand in 5 minutes is:

Solution

We know that the minute hand completes one rotation in 1 hour or 60 minutes. Therefore, area swept by the minute hand in 60 minutes = Area of the circle with radius equal to the length of the minute hand = Ï€r² Using unitary method, we get Area swept by minute hand in 1 minute = Ï€r²/60 Thus, area swept by minute hand in 5 minutes = (Ï€r²/60) × 5 = Ï€r²/12 Length of the minute hand (r) = 14 cm It is known that the minute hand completes one rotation in 1 hour or 60 minutes Therefore, the area swept by the minute hand in 60 minutes = Ï€r² Therefore, the area swept by the minute hand in 5 minutes = 5/60 × Ï€r² ⇒ 1/12 Ï€r² = 1/12 × 22/7 × 14 × 14 cm² = 154/3 cm²