Question

a circular disc of mass 0.15 kilogram and radius 0.1 metre make 120 revolutions in 1 minute about its own axis calculate the angular momentum​

Answer 1

Angular momemtum = 1.88 × $10^{-2}$ $kg.m^2/s$

Explanation:

Given,

Frequency = 120 rpm (revolution per minute)

∵ 1 minute = 120 revolutions

⇒ 60 sec   = 120 revolutions

∴ 1 sec   = 2 revolutions

u = 2 revolutions

∴ ω = 2πu = 2 × π × 2 rad/sec = 4π  $\frac{rad}{sec}$

V = ωr = 4π × 0.1 = 0.4π $\frac{m}{s}$

∴ Angular momentum = mVr

= 0.15 kg × 0.4π $\frac{m}{s}$ × 0.1 m

= 0.15 × 0.4 × 3.14 × 0.1

= 1.88 × $10^{-2}$ $Kg.m^2/s$

Hence, angular momemtum = 1.88 × $10^{-2}$ $kg.m^2/s$