Law of conservation of angular momentum
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- Torque acting on any particle is given by
If external torque acting on any particle is zero then,
- Hence in absence of external torque the angular momentum of the particle remains constant or conserved.
- Total torque acting on any system is given by
- If total external force acting on any particle system is zero or,
- If total external torque acting on any body is zero , then total angular momentum of the body remains constant or conserved.
Question 1 An ice skater spins with arms outstretch at 1.9 rev/s.Her moment of inertia at this time is 1.33 kgm^{2}.She pulls her arms to increase her rate of spin.Her moment of inertia after she pulls her arm is .48kgm^{2}.What is her new rate of spinning
a. 5.26 rev/s
b. 5.2 rev/s
c 4.7 rev/s
d. none of these
Solution 6
Law of conservation of angular momentum
I_{1}ω_{1}=I_{2}ω_{2}
or
1.33(1.9)=.48ω_{2}
or
ω_{2}=5.26 rev/s
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