Question

the linear speed of the seconds hand of a wall clock is 1.05 cm/s what will be the length of the seconds hand

Answer 1

in 60 sec the linear distance would be 60*1.05 = 63 cm. 
which is equal to circumference of the circle = 2*Pi*R = 63

R = 63/(2*pi) = 10.03 cm which is the length of the seconds hand.

Answer 2

Explanation:

linear speed = 1.05 cm/s

thus, in 1 second, it goes 1.05cm

in 1 second, it covers (630/60) = 6 degrees

\begin{lgathered}\frac{6}{360} \times 2 \pi \times l = 1.05\\\\ \Rightarrow l = \frac{1.05 \times 360}{6 \times 2 \pi } \\\\ \Rightarrow l = 10.03\ cm\end{lgathered}

360

6

×2π×l=1.05

⇒l=

6×2π

1.05×360

⇒l=10.03 cm