Question

A force + = (31 +4j+5k) N acts on an object and
displaces it through d = 5km. The total work
done by the force in this process is
[NCERT Pg. 117)
(1) 25 J
(2) 60 J
(3) 15 J
(4) 20 J​

Answer 1

identify...

Question:

Describe how work is done by a skater pulling in her arms during a spin. In particular, identify the force she exerts on each arm to pull it in and the distance each moves, noting that a component of the force is in the direction moved. Why is angular momentum not increased by this action?

Conservation of angular momentum:

The conservation of angular momentum is a physical law that states that the total angular momentum of a system will conserve if no external torques are applied within the system. Any change in the rotational inertia of a system will be equal to a change in the angular speed of the system, that will counteract any sort of change to the angular momentum. The angular momentum of a system is defined by the moment of inertia of a system times the angular speed of the system.

Answer and Explanation: 1

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The work done in rotational motion will be equal to the change in the rotational kinetic energy of the system. So work:

{eq}W=\tau \omega \\ \Delta...

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