Question

18.Which of the following is a Stable equilibrium? a.any form of equilibrium, because all equilibrium conditions are stable b.an equilibrium state where any small rotation results in a torque that acts produce rotation back in the opposite direction c. an equilibrium state where nothing is moving d.an equilibrium state where no torque is involved e. an equilibrium state where there is no net torque or net force 19.Which of the following is true about how the planets revolve around the sun and how the Sun rotates? a.The planets all revolve in one direction and the Sun rotates on its axis in the other direction. b.The Sun rotates on its axis in the opposite direction from the revolution of the planets and thus angular momentum is conserved. c. The planets revolve around the Sun in the same direction that the Sun rotates. d.The Sun does not rotate, but the planets all revolve around it in the same direction. e.There is no pattern to the rotation of all these bodies. 20.Why does the axis of rotation of a top change its direction as the top spins? a.Rotational kinetic energy causes the direction to shift b.. Angular momentum is conserved. c The inertia of the top keeps its orientation changing d.Conservation of rotational motion keeps the direction changing if it was changing to start. e Gravitational force exerts a torque on the top.

Answer 1

At equilibrium net force applied on the body is zero.

When body is at rest position at that time the no force applied on the body that position is equlibrequi position but if body experience a force and that the same force is is balanced by some other force then this position is also equilibrium position.hence equilibrium state where no force is involved is answer.

b) the sun doesn't rotate it is steady state and all the planets revolve around the sun in same direction due to gravitational Force of the sun.

c)the axis of rotation of top changes because of angular momentum is conserved .angu ang momentum is always constant as the rotation of top decreases the moment of inertia of top incraeinc and hence the effective mass of top increases and hence of change in moment of inertia the axis of rotation changes.