A wheel with moment of inertia 25 kg. m2 and angular velocity 10 rad/s begins to speed up, with angular acceleration 15 rad/sec2 . a) After 2 seconds of acceleration, how many radians of rotation has the wheel completed? b) After 3 seconds of acceleration, what is the wheel’s kinetic energy due to rotation?

Respuesta :

Answer:

(A) Angular speed 40 rad/sec

Rotation = 50 rad

(b) 37812.5 J

Explanation:

We have given moment of inertia of the wheel [tex]I=25kgm^2[/tex]

Initial angular velocity of the wheel [tex]\omega _0=10rad/sec[/tex]

Angular acceleration [tex]\alpha =15rad/sec^2[/tex]

(a) We know that [tex]\omega =\omega _0+\alpha t[/tex]

We have given t = 2 sec

So [tex]\omega =10+15\times  2=40rad/sec[/tex]

Now [tex]\Theta =\omega _0t+\frac{1}{2}\alpha t^2=10\times 2+\frac{1}{2}\times 15\times 2^2=50rad[/tex]

(b) After 3 sec [tex]\omega =10+15\times 3=55rad/sec[/tex]

We know that kinetic energy is given by [tex]Ke=\frac{1}{2}I\omega ^2=\frac{1}{2}\times 25\times 55^2=37812.5J[/tex]