Awheel is rotating freely with an angular speed of 800 rev/min on a shaft whose rotational inertia is negligible. a second wheel, initially at rest and twice the rotational inertia of the first, is suddenly coupled to the same shaft. we have to find(a) the angular speed of the resultant combination of the shaft and the two wheels; (b) the fraction of the original rotational kinetic energy lost in the process.

a)

b)

Explanation:

Given:

rotational speed of the wheel 1,

Let the rotational inertia of the wheel 1 be,

According to given, the rotational inertia of wheel 2,

(a)

According to the law of conservation of angular momentum:

(b)

initial kinetic energy:

Final kinetic energy:

∴the fraction of the original rotational kinetic energy lost in the process:

a cold ice-tea.

pour in room temperature or cold water. cover the pitcher and refrigerate. steep white or green tea for 6 to 8 hours; steep black or oolong tea for 8 to 12 hours.jun 28, 2015