Question

The length of hour hand of a wrist watch is 1.5 cm. Find magnitude linear velocity.
(Ans : 2.182 x 10⁻⁶ m/s)

Answer 1

length of hour hand of a wrist watch is 1.5cm.
we know, angular velocity , $\omega=\frac{2\pi}{T}$
here T is time taken to complete a circle.

$\omega=\frac{2\pi}{T}=\frac{2\pi}{12\times60\times60}\\\\=\frac{\pi}{12\times1800}$

we know, $v=\omega r$
v is the angular velocity, $\omega$ is the angular velocity and r is the radius of hour hand.

so, v = π/(12 × 1800) × 1.5
= π/(12 × 1200)
= π/14400
= 0.000218055556 m/s
= 2.18 × 10^-6 m/s

Answer 2

Hey there ...

As v = rw
= 15 × 10^-3 × 1.45 × 10^-4
v = 21.81 × 10^-7
v = 2.181 × 10^-6 m/sec .

And it's approximately you can take Ans as 2.182 × 10^-6 m/sec .

Hope it will help you..