Let A be a unit vector along the axis of rotation of a purely rotating body and g be a unit vector along the velocity of a particle P of the body away from the axis. The value of A . B is
(a) 1
(b) -1
(c) 0
(d) None of these.
1 Answers
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A body is uniformly rotating about an axis fixed in an inertial frame of reference. Let A be a unit vector along the axis of rotation
(c) 0 Explanation: Since the body is uniformly rotating, the resultant force on the particle P will be in the radial direction. So again the directions of A and B will be...
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A body is rotating uniformly about a vertical axis fixed in an inertial frame. The resultant force on a particle of the body not on the axis is
(c) horizontal and intersecting the axis Explanation: Since the body is rotating uniformly, a particle not on the axis moves in a uniform circular motion. This circle will be horizontal with its center at...
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A person sitting firmly over a rotating stool has his arms stretched. If he folds his arms, his angular momentum about the axis of rotation
(c) remains unchanged Explanation: If there is no external torque, the angular momentum is conserved. It is true if the moment of inertia of the rotating part of the stool is negligible...
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The axis of rotation of a purely rotating body (a) must pass through the centre of mass
(b) may pass through the centre of mass (d) may pass through a particle of the body. Explanation: It is not a necessary condition that the axis of rotation should pass through the center of...
1 Answers 1 views
The non-zero vectors vector a, vector b and vector c are related by vector a = 8vector b and vector c = - 7vector b.
(a) : vector a = 8vector b vector c = - 7vector b vector a and vector b are parallel and vector b and vector c are antiparallel. Thus vector a and vector c are...
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The resultant of vector A and vector B makes an angle a with vector A and β with vector B, (a) α < β
The correct answer is (c) α < β if A > B
1 Answers 1 views
Let vector C = vector A + vector B. (a) | vector C | is always greater than | vector A |
(b) It is possible to have | vector C | < | vector A | and | vector C | < | vector B |
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Let the angle between two nonzero vectors vector A and vector B be 120° and its resultant be vector C.
(c) C must be greater than | A - B|
1 Answers 2 views
The axis of rotation of a purely rotating body (a) must pass through the centre of mass,
(b) may pass through the centre of mass (d) may pass through a particle of the body. Explanation: It is not a necessary condition that the axis of rotation should pass through the...
1 Answers 1 views
If vector α=3i-j and vector β=2i+j-3k,then express vector β in the form vector β =vector β1+vector β2,
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