JEE Questions for Physics Systems Of Particles And Rotational Motion Quiz 10 - MCQExams.com

A door 1.6 m wide requires a force of 1 N to be applied at the free end to open or close it. The force that is required at a point 0.4 m distant from the hinges for opening or closing the door is
  • 1.2 N
  • 3.6 N
  • 2.4 N
  • 4 N
A wheel of radius 0.4 m can rotate freely about its axis as shown in the figure. A string is wrapped over its rim and a mass of 4 kg is hung. An angular acceleration of 8 rad–s–2 is produced in it due to the torque. Then, moment of inertia of the wheel is (g = 10 ms–2)
Physics-Systems of Particles and Rotational Motion-89650.png
  • 2 kg–m2
  • 1 kg–m2
  • 4 kg–m2
  • 8 kg–m2

Physics-Systems of Particles and Rotational Motion-89652.png

  • Physics-Systems of Particles and Rotational Motion-89653.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89654.png

  • Physics-Systems of Particles and Rotational Motion-89655.png

  • Physics-Systems of Particles and Rotational Motion-89656.png
A disc of moment of inertia 5 kg–m2 is acted upon by a constant torque of 40 N–m. Starting from rest the time taken by it to acquire an angular velocity of 24 rad/sec is
  • 3 sec
  • 4 sec
  • 2.5 sec
  • 120 sec

Physics-Systems of Particles and Rotational Motion-89659.png
  • Zero
  • 2)
    Physics-Systems of Particles and Rotational Motion-89660.png

  • Physics-Systems of Particles and Rotational Motion-89661.png

  • Physics-Systems of Particles and Rotational Motion-89662.png
A constant torque of 1000 N–m, turns a wheel of moment of inertia 200 kg–m2 about an axis through the centre. Angular velocity of the wheel after 3s will be
  • 15 rad/s
  • 10 rad/s
  • 5 rad/s
  • 1 rad/s
What constant force, tangential to the equator should be applied to the earth to stop its rotation in one day?
  • 1.3 × 1022 N
  • 8.26 × 1028 N
  • 1.3 × 1023 N
  • None of these
Very thin ring of radius R is rotated about its centre. It\'s radius will
  • Increase
  • Decrease
  • Change depends on the material
  • None of the above

Physics-Systems of Particles and Rotational Motion-89667.png
  • 1
  • R1/R2
  • R2/R1
  • (R1/R2)2
A horizontal force F is applied such that the block remains stationary then which of the following statement is false
Physics-Systems of Particles and Rotational Motion-89669.png
  • f = mg [where f is the friction force]
  • F = N [where N is the normal force]
  • F will not produce torque
  • N will not produce torque
Turning effect is produced by
  • Tangential component of force
  • Radial component of force
  • Transverse component of force
  • None of the above
In the figure (i) half of the meter scale is made of wood while the other half, of steel. The wooden part is pivoted at O. A force F is applied at the end of steel part. In figure (ii) the steel part is pivoted at O and the same force is applied at the wooden end
Physics-Systems of Particles and Rotational Motion-89672.png
  • More acceleration will be produced in (i)
  • More acceleration will be produced in (ii)
  • Same acceleration will be produced in both conditions
  • Information is incomplete
A fly wheel of moment of inertia 3 × 102 kg–m2 is rotating with uniform angular speed of 4.6 rad s–1. If a torque of 6.9 × 102 N–m retards the wheel, then the time in which the wheel comes to rest is
  • 1.5 s
  • 2 s
  • 0.5 s
  • 1 s
Torque applied on a particle is zero, then its angular momentum will be
  • Equal in direction
  • Equal in magnitude
  • Both (a) and (b)
  • Neither (a) nor (b)
A particle of mass m moves along line PC with velocity v as shown. What is the angular momentum of the particle about O?
Physics-Systems of Particles and Rotational Motion-89676.png
  • mvL
  • mvl
  • mvr
  • Zero
A thin and circular disc of mass M and radius R is rotating in a horizontal plane about an axis passing through its centre and perpendicular to its plane with an angular velocity ω. If another disc of same dimensions but of mass M/4 is placed gently on the first disc co–axially, then the new angular velocity of the system is

  • Physics-Systems of Particles and Rotational Motion-89678.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89679.png

  • Physics-Systems of Particles and Rotational Motion-89680.png

  • Physics-Systems of Particles and Rotational Motion-89681.png
The angular speed of a body changes from ω1 to ω2 without applying a torque but due to change in its moment of inertia. The ratio of radii of gyration in the two cases is

  • Physics-Systems of Particles and Rotational Motion-89683.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89684.png

  • Physics-Systems of Particles and Rotational Motion-89685.png

  • Physics-Systems of Particles and Rotational Motion-89686.png
Angular momentum of a system of particles changes when
  • Force acts on a body
  • Torque acts on a body
  • Direction of velocity changes
  • None of the above
If a force acts on a body at a point away from the centre of mass, then
  • None of the above
  • Linear acceleration changes
  • Angular acceleration changes
  • Both change
The rotational kinetic energy of a body is E and its moment of inertia is I. The angular momentum is
  • EI
  • 2)
    Physics-Systems of Particles and Rotational Motion-89688.png

  • Physics-Systems of Particles and Rotational Motion-89689.png
  • E / I
What remains constant in the field of central force?
  • Potential energy
  • Kinetic energy
  • Angular momentum
  • Linear momentum
A cockroach is moving with velocity v in anticlockwise direction on the rim of a disc of radius R of mass m. The moment of inertia of the disc about the axis is I and it is rotating in clockwise direction with an angular velocity ω. If the cockroach stops, the angular velocity of the disc will be

  • Physics-Systems of Particles and Rotational Motion-89692.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89693.png

  • Physics-Systems of Particles and Rotational Motion-89694.png

  • Physics-Systems of Particles and Rotational Motion-89695.png
The principle of conservation of angular momentum, states that angular momentum
  • Always remains conserved
  • Is the product of moment of inertia and velocity
  • Remains conserved until the torque acting on it remains constant
  • None of the above
A particle performs uniform circular motion with an angular momentum L. If the frequency of a particle\'s motion is doubled and its kinetic energy is halved, the angular momentum becomes
  • 2 L
  • 4 L
  • L/2
  • L/4
A person standing on a rotating platform has his hands lowered. He suddenly outstretch his arms. The angular momentum
  • Becomes zero
  • Increases
  • Decreases
  • Remains the same
What remains constant when the earth revolves around the sun?
  • Angular momentum
  • Linear momentum
  • Angular kinetic energy
  • Linear kinetic energy
A circular turn table has a block of ice placed at its centre. The system rotates with an angular speed ω about an axis passing through the centre of the table. If the ice melts on its own without any evaporation, the speed of rotation of the system
  • Becomes zero
  • Remains constant at the same value ω
  • Increases to a value greater than ω
  • Decreases to a value less than ω
A boy stands over the centre of a horizontal platform which is rotating freely with a speed of 2 revolutions/sec about a vertical axis through the centre of the platform and straight up through the boy. He holds 2 kg masses in each of his hands close to his body. The combined moment of inertia of the system is 1 kg × m2. The boy now stretches his arms so as to hold the masses of inertia of the system increases to 2 kg × m2. The kinetic energy of the system in the latter case as compared with that in the previous case will
  • Remain unchanged
  • Decrease
  • Increase
  • Remain uncertain
A homogeneous disc of mass 2 kg and radius 15 cm is rotating about its axis (which is fixed) with an angular velocity of 4 radian/s. The linear momentum of the disc is
  • 1.2 kg–m/s
  • 1.0 kg–m/s
  • 0.6 kg–m/s
  • None of these
If the earth is a point mass of 6 × 1024 kg revolving around the sun at a distance of 1.5 × 108 km and in time T = 3.14 × 107s, then the angular momentum of the earth around the sun is
  • 1.2 × 1018 kgm2/s
  • 1.8 × 1029 kgm2/s
  • 1.5 × 1037 kgm2/s
  • 2.7 × 1040 kgm2/s
A boy comes running and sits on a rotating platform. What is conserved?
  • Linear momentum
  • Kinetic energy
  • Angular momentum
  • None of these
A man turns on a rotating table with an angular speed ω. He is holding two equal masses at arm\'s length. Without moving his arms, he just drops the two masses. How will his angular speed change?
  • It will be less than ω
  • It will be more than ω
  • It will remains equal to ω
  • May be less than, greater than or equal to ω depending on the quantity of masses
A small object of mass m is attached to a light string which passes through a hollow tube. The tube is hold by one hand and the string by the other. The object is set into rotation in a circle of radius R and velocity v. The string is then pulled down, shortening the radius of path of r. What is conserved?
  • Angular momentum
  • Linear momentum
  • Kinetic energy
  • None of these
A swimmer while jumping into water from a height easily forms a loop in the air, if
  • He pulls his arms and legs in
  • He spreads his arms and legs
  • He keeps himself straight
  • None of the above
A ring of mass 10 kg and diameter 0.4 m is rotated about its axis. If it makes 2100 revolutions per minute, then its angular momentum will be
  • 44 kg × m2/s
  • 88 kg × m2/s
  • 4.4 kg × m2/s
  • 0.4 kg × m2/s
A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which one of the following will not be affected
  • Moment of inertia
  • Angular momentum
  • Angular velocity
  • Rotational kinetic energy
Calculate the angular momentum of a body whose rotational energy is 10 joule. If the angular momentum vector coincides with the axis of rotation and its moment of inertia about this axis is 8 × 10–7 kg/m2
  • 4 × 10–3 kg m2/s
  • 2 × 10–3 kg m2/s
  • 6 × 10–2 kg m2/s
  • None of the above
If the earth is treated as a sphere of radius R and mass M. Its angular momentum about the axis of rotation with period T is

  • Physics-Systems of Particles and Rotational Motion-89704.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89705.png

  • Physics-Systems of Particles and Rotational Motion-89706.png

  • Physics-Systems of Particles and Rotational Motion-89707.png
If the polar ice caps melt suddenly
  • The length of day will be more than 24 hours
  • The length of the day will less than 24 hours
  • The length of the day will remain same as 24 hours
  • The length of the day will become more than 24 hours initially and then becomes equal to 24 hours
A thin horizontal circular disc is rotating about a vertical axis passing through its centre. An insect is at rest at a point near the rim of the disc. The insect now moves along a diameter of the disc to reach other end. During the journey of the insect, then angular speed of the disc
  • Remains unchanged
  • Continuously decreases
  • Continuously increases
  • First increases and then decreases
A body moves with constant velocity v is a straight line parallel to x–axis. The angular momentum with respect to origin is
  • Zero
  • Constant
  • Continuously increases
  • Continuously decrease
The total kinetic energy of a body of mass 10 kg and radius 0.5 m moving with a velocity of 2 m/s without slipping is 32.8 J. The radius of gyration of the body is
  • 0.25 m
  • 0.2 m
  • 0.5 m
  • 0.4 m
A ring of radius 0.5 m and mass 10 kg is rotating about its diameter with angular velocity of 20 rad/s. Its kinetic energy
  • 10 J
  • 100 J
  • 500 J
  • 250 J
A sphere of mass 0.5 kg and diameter 1m rolls without sliding with a constant velocity of 5 m/s, calculate what is the ratio of the rotational K.E. to the total kinetic energy of the sphere

  • Physics-Systems of Particles and Rotational Motion-89713.png
  • 2)
    Physics-Systems of Particles and Rotational Motion-89714.png

  • Physics-Systems of Particles and Rotational Motion-89715.png

  • Physics-Systems of Particles and Rotational Motion-89716.png
The moment of inertia of two freely rotating bodies A and B are IA and IB respectively. IA > IB and their angular momentum are equal. If KA and KB are their kinetic energies, then
  • KA = KB
  • KA > KB
  • KA < KB
  • KA = 2KB
. A thin hollow cylinder open at both ends
(i) Sliding without rolling
(ii) Rolls without slipping, with the same speed The ratio of kinetic energy in the two cases is
  • 1 : 1
  • 4 : 1
  • 1 : 2
  • 2 : 1
A body of moment of inertia of 3 kg–m2 rotating with an angular velocity of 2 rad/sec has the same kinetic energy as a mass of 12 kg moving with a velocity of
  • 8 m/s
  • 0.5 m/s
  • 2 m/s
  • 1 m/s
If the angular momentum of a rotating body about a fixed axis is increased by 10%. Its kinetic energy will be increased by
  • 10%
  • 20%
  • 21%
  • 5%
A body is rolling down an inclined plane. If K.E. of rotation is 40% of K.E. in translatory state, then the body is a
  • Ring
  • Cylinder
  • Hollow ball
  • Solid ball
A flywheel is in the form of solid circular wheel of mass 72 kg and radius of 0.5 m and it takes 70 r.p.m., then the energy of revolution is
  • 24 J
  • 240 J
  • 2.4 J
  • 2400 J
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Physics Quiz Questions and Answers