Question

Identify the increasing order of the angular velocities of the following:
a) earth rotating about its own axis
b) hours hand of a clock
c) seconds hand of a clock
d) fly wheel of radius 2m making 300 rps

• A. a, b, c, d
• B. b, c, d, a
• C. c, d, a, b
• D. d, a, b, c

Answer 1

Answer: (A)

a, b, c, d

Time periods of rotation of earth $=24hrs$.
Hours hand $=12hrs$
Second hands $=1min$
$flywheel=\frac{2\pi }{\omega }=\frac{2\pi }{300\times \frac{2\pi }{60}}=\frac{1}{5}sec$
$\therefore \omega =\frac{2\pi }{T}\Rightarrow \omega \alpha \frac{1}{T}$
$\therefore$ increasing order is a,b,c,d.