Rotation, angular momentum and inertia

[aks_sky]

The rotor of an electric motor has I<sub>m= 2 x 10 ^-3 Kg.m²
about its central axis. The motor is used to change the orientation of a space probe in which it is mounted. If the axis of the motor is mounted parallel to the axis of the probe (Ip= 12 Kg.m^2) calculate the number of rotations required to turn the probe through 30 degrees about its axis.


** I have tried the formula for anuglar momentum and torque here also i have tried to find the ratio between the two bodies but i do not get the correct answer. The answer should be 498 revs but i don't get it right. What else can i try?</sub>

 

[tiny-tim]

The rotor of an electric motor has I<sub>m= 2 x 10 ^-3 Kg.m²
about its central axis. The motor is used to change the orientation of a space probe in which it is mounted. If the axis of the motor is mounted parallel to the axis of the probe (Ip= 12 Kg.m^2) calculate the number of rotations required to turn the probe through 30 degrees about its axis.


** I have tried the formula for anuglar momentum and torque here also i have tried to find the ratio between the two bodies but i do not get the correct answer. The answer should be 498 revs but i don't get it right. What else can i try?</sub>

<sub>Hi aks_sky!

Just use conservation of angular momentum …

it starts zero, so it stays zero!

(and remember 30º = 1/12 of a revolution)</sub>

 

[aks_sky]

sweet.. all sorted.. thank u