๐Ÿ“ข Too many exams? Donโ€™t know which one suits you best? Book Your Free Expert ๐Ÿ‘‰ call Now!

  • google app store apple app store
  • โœ–

      Question

      Length of a minute hand of a clock is 14 cms. Area swept

      bv the minute hand in 5 minutes is:
      A 154 sq cms Correct Answer Incorrect Answer
      B 154/3 sq cms Correct Answer Incorrect Answer
      C 210 sq cms Correct Answer Incorrect Answer
      D 154/โˆš3 sq cms Correct Answer Incorrect Answer

      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 = ฯ€r2 Using unitary method, we get Area swept by minute hand in 1 minute = ฯ€r2/60 Thus, area swept by minute hand in 5 minutes = (ฯ€r2/60) ร— 5 = ฯ€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 = ฯ€r2 Therefore, the area swept by the minute hand in 5 minutes = 5/60 ร— ฯ€r2 โ‡’ 1/12 ฯ€r2 = 1/12 ร— 22/7 ร— 14 ร— 14 cm2 = 154/3 cm2

      Practice Next
      ask-question