The minute hand of a clock is $1.5$ cm long. How far does its tip travel in $40$ minutes? (Use $\pi = 3.14$.)
A$6.28$ cm
B$4.71$ cm
C$3.14$ cm
D$9.42$ cm
Answer & Solution
Correct answer: A. $6.28$ cm
In 60 minutes the minute hand completes $2\pi$ rad. In 40 minutes: $\theta = \dfrac{40}{60} \cdot 2\pi = \dfrac{4\pi}{3}$ rad.
$l = r\theta = 1.5 \cdot \dfrac{4\pi}{3} = 2\pi \approx 6.28$ cm.
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