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The second hand on a clock is 8 cm long. How long does it travel in 10 minutes? I must round.

User Yukari
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1 Answer

5 votes

Answer:

502.65 cm

Explanation:

The angle through which the second hand moves is 2π radians per minute. Then in 10 minutes, it covers an arc of ...

(10 min)(2π rad/min) = 20π radians

The length of the arc traversed by the tip of the hand is given by ...

s = rθ

where θ is the angle in radians, and r is the radius of the arc.

For the given arc angles and radius, the distance traveled by the tip of the second hand in 10 minutes is ...

s = (8 cm)(20π radians) = 160π cm ≈ 502.65 cm

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We have used the "pi button" value of π. If you use 3.14, you will get a different answer. This value is correctly rounded to 2 decimal places. You can round it to whatever precision your problem requires.

User Bill DeRose
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