JEE Questions for Physics Systems Of Particles And Rotational Motion Quiz 8 - MCQExams.com

The distance between the carbon atom and the oxygen atom in a carbon monoxide molecule is 1.1 Å. Given mass of carbon atom is 12 a.m.u., and mass of oxygen atoms is 16 a.m.u. calculate the position of the centre of mass of the carbon monoxide molecule,
  • 6.3 Å from the carbon atom
  • 1 Å from the oxygen atom
  • 0.63 Å from the carbon atom
  • 0.12 Å from the oxygen atom
A rod of mass m and length l is made to stand at an angle of 60° with the vertical. Potential energy of the rod in this position is

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    Physics-Systems of Particles and Rotational Motion-89405.png

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Look at the drawing given in the figure which has been drawn with ink of uniform line-thickness. The mass of ink used to draw each of the two inner circles, and each of the two line segments is m. The mass of the ink used to draw the outer circle is 6m. The co-ordinates of the centres of the different parts are : outer circle (0, 0), left inner circle (–a, a), right inner circle (a, a), vertical line (0,and horizontal line (0, – a). The y-coordinate of the centre of mass of the ink in this drawing is
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    Physics-Systems of Particles and Rotational Motion-89411.png

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Four particle of masses m, 2m, 3m and 4m are arranged at the corners of a parallelogram with each side equal to a and one of the angle between two adjacent sides is 60°. The parallelogram lies in the x–y plane with mass m at the origin and 4 m on the x-axis. The centre of mass of the arrangement will be located at

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    Physics-Systems of Particles and Rotational Motion-89416.png

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  • Physics-Systems of Particles and Rotational Motion-89418.png
Masses 8, 2, 4, 2 kg are placed at the corners A, B, C, D respectively of a square ABCD of diagonal 80 cm. The distance of centre of mass from A will be
  • 20 cm
  • 30 cm
  • 40 cm
  • 60 cm
Three identical metal balls each of radius r are placed touching each other on a horizontal surface such that an equilateral triangle is formed, when centres of three balls are joined. The centre of the mass of system is located at
  • Horizontal surface
  • Centre of one of the balls
  • Line jointing centres of any two balls
  • Point of intersection of the medians
Centre of mass is a point
  • Which is geometric centre of a body
  • From which distance of particles are same
  • Where the whole mass of the body is supposed to concentrated
  • Which is the origin of reference frame

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    Physics-Systems of Particles and Rotational Motion-89423.png

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The centre of mass of triangle shown in figure has co-ordinates
Physics-Systems of Particles and Rotational Motion-89427.png

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    Physics-Systems of Particles and Rotational Motion-89429.png

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A thin uniform rod of length l and mass m is swinging freely about a horizontal axis passing through its end. Its maximum angular speed is co. Its centre of mass rises to a maximum height of

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    Physics-Systems of Particles and Rotational Motion-89434.png

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  • Physics-Systems of Particles and Rotational Motion-89436.png
The centre of mass of a system of two particles divides the distance between them
  • In inverse ratio of square of masses of particles
  • In direct ratio of square of masses of particles
  • In inverse ratio of masses of particles
  • In direct ratio of masses of particles
If linear density of a rod of length 3m varies as λ = 2 + x, then the position of the centre of gravity of the rod is

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    Physics-Systems of Particles and Rotational Motion-89440.png

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    Physics-Systems of Particles and Rotational Motion-89446.png

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A body A of mass M while falling vertically downwards under gravity breaks into two parts a body B of mass 1/3 M and a body C of mass 2/3M. The centre of mass of bodies B and C taken together shifts compared to that of body A towards
  • Body C
  • Body B
  • Depends on height of breaking
  • Does not shift
Four bodies of equal mass start moving with same speed as shown in the figure. In which of the following combination the centre of mass will remain at origin
Physics-Systems of Particles and Rotational Motion-89450.png
  • c and d
  • a and b
  • a and c
  • b and d
Three identical spheres, each of mass 1 kg are kept as shown in figure, touching each other, with their centres on a straight line. If their centres are marked P, Q, R respectively, the distance of centre of mass of the system from P is
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    Physics-Systems of Particles and Rotational Motion-89453.png

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An isolated particle of mass m is moving in a horizontal plane (X–Y) along the X–axis at a certain height above the ground. It suddenly explodes into two fragments of masses m/4 and 3m/4. An instant later, the smaller fragment is at y = 15 cm. The larger fragment of this instant is at
  • y = –5 cm
  • y = +20 cm
  • y = +5 cm
  • y = –20 cm
Centre of mass of 3 particles 10 kg, 20 kg and 30 kg is at (0, 0, 0). Where should a particle of mass 40 kg be placed so that the combination centre of mass will be at (3, 3, 3)?
  • (0, 0, 0)
  • (7.5, 7.5, 7.5)
  • (1, 2, 3)
  • (4, 4, 4)
A circular disc of radius R is removed from a bigger circular disc of radius 2R such that the circumferences of the discs coincide. The centre of mass of the new disc is αR from the centre of the bigger disc. The value of a is
  • 1/3
  • 1/2
  • 1/6
  • 1/4
Two masses m1 and m2 (m1 > m2) are connected by massless flexible and inextensible string passed over massless and frictionless pulley. The acceleration of centre of mass is

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    Physics-Systems of Particles and Rotational Motion-89461.png

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  • Zero
Two point objects of masses 1.5 g and 2.5 g respectively are at a distance of 16 cm apart, the centre of gravity is at a distance x from the object of mass 1.5 g where x is
  • 10 cm
  • 6 cm
  • 13 cm
  • 3 cm
A system consists of 3 particles each of mass m located at points ( 1, 1), (2,and (3, 3). The co-ordinates of the centre of mass are
  • (6, 6)
  • (3, 3)
  • (1, 1)
  • (2, 2)
Two particles of masses 1 kg and 2 kg are located at x1 = 0, y1 = 0 and x2 = 1, y2 = 0

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    Physics-Systems of Particles and Rotational Motion-89467.png

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Three bricks each of length L, and mass M are arranged as shown from the wall. The distance of the centre of mass of the system from the wall is
Physics-Systems of Particles and Rotational Motion-89470.png
  • L/4
  • L/2
  • (3.2)L
  • (11/12)L
The angular velocity of a wheel increases from 100 rps to 300 rps in 10 seconds. The number of revolutions made during that time is
  • 600
  • 1500
  • 2000
  • 3000
In a bicycle the radius of rear wheel is twice the radius of front wheel. If rF and rr are the radius, vF and vr are speeds of top most points of wheel, then
  • vr = 2vF
  • vF = 2vr
  • vF = vr
  • vF > vr
The moment of inertia of a body about a given axis is 2.4 kg–m2. To produce a rotational kinetic energy of 750 J, an angular acceleration of 5 rad/s2 must be applied about that axis for
  • 6 sec
  • 5 sec
  • 4 sec
  • 3 sec
If the earth shrinks such that its mass does not change but radius decreases to one quarter of its original value then one complete day will take
  • 96 hr
  • 48 hr
  • 6 hr
  • 1.5 hr
A flywheel gains a speed of 540 r.p.m. in 6 sec. Its angular acceleration will be
  • 3 π rad/sec2
  • 9 π rad/sec2
  • 18 π rad/sec2
  • 54 π rad/sec2
The wheel of a car is rotating at the rate of 1200 revolutions per minute. On pressing the accelerator for 10 seconds. It starts rotating at 4500 revolutions per minute. The angular acceleration of the wheel is
  • 1880 degrees/second 2
  • 30 radians/second 2
  • 40 radians/second 2
  • 1980 degrees/second 2
A torque of 50 Nm acting on a wheel at rest rotates it through 200 radians in 5 sec. Calculate the angular acceleration produced
  • 8 rad/sec2
  • 4 rad/sec2
  • 16 rad/sec2
  • 12 rad/sec2
A wheel has a speed of 1200 revolutions per minute and is made to slow down at a rate of 4 radians/s2. The number of revolutions it makes before coming to rest is
  • 143
  • 272
  • 314
  • 722
A wheel is rotating at 900 r.p.m. about its axis. When the power is cut–off, it comes to rest in 1 minute. The angular retardation in radian/s2 is
  • π /2
  • π /4
  • π /6
  • π /8
In which case application of angular velocity is useful?
  • When a body is rotating
  • When velocity of body is in a straight line
  • When acceleration of body is in a straight line
  • None of the above
Consider a disc rotating in the horizontal plane with a constant angular speed ω about its centre O. The disc has a shaded region on one side of the diameter and an unshaded region on the other side as shown in the figure. When the disc is in the orientation as shown, two pebbles P and Q are simultaneously projected at an angle towards R. The velocity of projection is in the y–z plane and is same for both pebbles with respect to the disc. Assume that (i) they land back on the disc before the disc has completed 1/8 rotation, (ii) their range is less than half the disc radius, and (iii) ω remains constant throughout. Then
Physics-Systems of Particles and Rotational Motion-89481.png
  • P lands in the shaded region and Q in the unshaded region
  • P lands in the unshaded region and Q in the shaded region
  • both P and Q land in the unshaded region
  • both P and Q land in the shaded region
If linear velocity is constant then angular velocity is proportional to
  • 1/r
  • 1/r2
  • 1/r3
  • 1/r5
A uniform disk of mass M and radius R is mounted on a fixed horizontal axis. A block of mass m hangs from a mass less string that is wrapped around the rim of the disk. The magnitude of the acceleration of the falling block (m) is

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Two discs of the same material and thickness have radii 0.2 m and 0.6 m. Their moments of inertia about their axes will be in the ratio
  • 1 : 81
  • 1 : 27
  • 1 : 9
  • 1 : 3
The moment of inertia of a metre scale of mass 0.6 kg about an axis perpendicular to the scale and located at the 20 cm position on the scale in kg–m2 is (Breadth of the scale is negligible)
  • 0.074
  • 0.104
  • 0.148
  • 0.208
Moment of inertia along the diameter of a ring is

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    Physics-Systems of Particles and Rotational Motion-89492.png

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A sphere of mass 10 kg and radius 0.5m rotates about a tangent. The moment of inertia of the solid sphere is
  • 5 kg–m2
  • 2.7 kg–m2
  • 3.5 kg–m2
  • 4.5 kg–m2
The moment of inertia of semicircular ring about an axis which is perpendicular to the plane of the ring and passes through the centre]

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    Physics-Systems of Particles and Rotational Motion-89497.png

  • Physics-Systems of Particles and Rotational Motion-89498.png
  • None of these
Moment of inertia of a uniform circular disc about a diameter is I. Its moment of inertia about an axis perpendicular to its plane and passing through a point on its rim will be
  • 5 I
  • 6 I
  • 3 I
  • 4 I
Moment of inertia depends on
  • Distribution of particles
  • Mass
  • Position of axis of rotation
  • All of the above
The moment of inertia of a straight thin rod of mass M and length l about an axis perpendicular to its length and passing through its one end, is
  • Ml2 / 12
  • Ml2 / 3
  • Ml2 / 2
  • Ml2
Analogue of mass in rotational motion is
  • Moment of inertia
  • Angular momentum
  • Torque
  • None of these
From a uniform wire, two circular loops are made (i) P of radius r and (ii) Q of radius nr. If the moment of inertia of Q about an axis passing through its centre and perpendicular to its plane is 8 times that of P about a similar axis, the value of n is (diameter of the wire is very much smaller than r or nr)
  • 8
  • 6
  • 4
  • 2
A circular thin disc of mass 2 kg has a diameter 0.2 m. Calculate its moment of inertia about an axis passing through the edge and perpendicular to the plane of the disc (in kg–m2)
  • 0.01
  • 0.03
  • 0.02
  • 3
The moment of inertia of a uniform ring of mass M and radius r about a tangent lying in its own plane is
  • 2Mr2
  • 3/2Mr2
  • Mr2
  • 1/2 Mr2
The moment of inertia of a sphere of mass M and radius R about an axis passing through its centre is 2/5MR2. The radius of gyration of the sphere about a parallel axis to the above and tangent to the sphere is

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