Rotational Mechanics Conceptual Questions
Here find good conceptual questions on Rotational Mechanics. Rotational mechanics questions can be bit tricky so you need to attempt them carefully.
1) If the total external force acting on a rigid body is zero, then
(a) only linear momentum remains constant
(b) only angular momentum remains constant
(c) both linear momentum and angular momentum remains constant
(d) neither linear momentum nor angular momentum remain constant
2) A ball of mass M is tied to a string of length L is whirled round in a horizontal plane in a circle of radius R. The speed of the stone is increased beyond the maximum permissible value and the string breaks suddenly; then
(a) the stone will jerk radially outwards
(b) the stone will jerk radially inwards
(c) the stone will fly off tangentially from the instant the string breaks
(d) None of the above
3) Which of the following statements is false
(a) During rolling the force of friction acts in the same direction as the direction of motion of the centre of mass of the body
(b) The instantaneous speed of the point of contact during rolling is zero
(c) The instantaneous acceleration of the point of contact during rolling is zero
(d) For perfect rolling, work done against friction is zero
4) For a particle rotating about a fixed axis with non?uniform angular velocity, there
(a) is only radial acceleration
(b) is only tangential acceleration
(c) is neither radial nor tangential acceleration
(d) are both radial acceleration and tangential acceleration
5) The moment of inertia plays the same role in rotational motion as is played in linear motion by
6) The trajectory of a ‘fixed’ point on the rain of a wheel of a vehicle as the vehicle moves with a constant speed is being observed by an observer fixed on ground. The trajectory, as noted by him will be
(a) a circle coinciding with circumference of the wheel repeating itself
(b) a parabola with vertex at the highest point on the wheel
(c) a straight line parallel to road
(d) a cycloid, repeating itself with every rotation of the wheel
7) A jet engine works on the principle of conservation of
(c) linear momentum
(d) Angular momentum
e) None of the above
8). A rectangular container half full of oil is being carried by a train on a horizontal track. If the train accelerates, the surface of the oil in the container with respect to horizontal surface will
(a) be raised upward from the front
(b) be raised in the middle
(c) be raised upward from the back
(d) remain unchanged
e) Not sufficent information
9) The centre of mass of a system of two particles is
(a) on the line joining then and midway between them
(b) on the line joining them at a point whose distance from each particle is proportional to the square of the mass f the
(c) on the line joining them and at a point whose distance from each particle is proportional inversely to the mass of
(d) on the line joining them and at a point whose distance from each particle is proportional to the mass of that particle
10)Of the two spheres of same size, mass and appearance one is hollow and other is solid. If the two are rolled down an inclined plane simultaneously, then
(a) hollow sphere will reach the bottom first
(b) solid sphere will reach the bottom first
(c) both will reach bottom together
(d) either can reach first depending upon the surface of the plane
11) A shell fired from a gun at an angle to the horizontal explodes in mid air. The centre of mass of the shell fragments will have
(a) vertically down
(c) along the same parabolic path of the unexploded shell
(d) along the tangent to the parabolic path of unexploded shell
12) If a particle moves in the x – y plane, its angular momentum
vector is in the
a) x -direction
b) z- direction
c) y -direction
d) x-y direction
13) At a given moment, the total angular momentum of a system of two particles about a certain point is zero. Accordingly we know that the particles
(A) must both be at rest.
(B) must be moving on the same circle in opposite directions.
(C) must be moving on straight perpendicular paths.
(D) must have the same magnitude linear momentum.
(E) None of the above statements are correct
14) A particle of mass m and speed v has zero angular momentum with respect to a point Z in space. We know that the particle
(A) will never pass through Z
(B) is moving along a line that is perpendicular to the plane containing it and Z
(C) is moving along a line that passes through Z
(D) must have already passed through point Z
(E) Not sufficient information
15)Two initially stationary skaters, of unequal mass( M ,m and M > m) face each other on a frictionless horizontal ice surface. If they push apart, which one of the following statements is true?
(A) The skater (M) experiences twice the magnitude force experienced by the skater(m).
(B) The skater(m) experiences twice the magnitude impulse experienced by the skater(M)
(C) After separation, both skaters have the same speed.
(D) After separation, both skaters have the same kinetic energy.
(E) After separation, both skaters have momenta of equal magnitude but in opposite directions.