Question

A clock has a minute hand of length $14cm$. At what speed does the tip of the minute hand move in a duration of half an hour?

• A. $\frac{7}{450}cm{s}^{-1}$
• B. $\frac{11}{450}cm{s}^{-1}$
• C. $\frac{44}{450}cm{s}^{-1}$
• D. $\frac{16}{750}cm{s}^{-1}$

Answer 1

Answer: (B)

$\frac{11}{450}cm{s}^{-1}$

Length of minute hour hand,

$r=14cm$

Covered distance in half an hour,

$d=\pi r$

time taken to complete this motion,

$t=30min$

$\Rightarrow t=30\times 60s$

$\Rightarrow t=1800s$

So speed of the tip of the minute hour-

$V=\frac{d}{t}$

$\Rightarrow V=\frac{\pi r}{t}$

$\Rightarrow V=\frac{\frac{22}{7}\times 14}{1800}$

$\Rightarrow V=\frac{11}{450}cm{s}^{-1}$