CBSE Questions for Class 11 Engineering Physics Systems Of Particles And Rotational Motion Quiz 1 - MCQExams.com

A rigid massless rod of length 3$$l$$ has two masses attached art each end as shown in the figure. The rod is pivoted at point P on the horizontal position, its instantaneous angular acceleration will be: 
1333983_0e3078a175c3467c9a74b436ea0b96ff.PNG
  • $$\dfrac{g}{2l}$$
  • $$\dfrac{7g}{3l}$$
  • $$\dfrac{g}{13l}$$
  • $$\dfrac{g}{3l}$$
A rod of length 50 cm is pivoted at one end. It is raised such that if makes an angle of $$30^o$$ from the horizontal as shown and released from rest. Its angular speed when it passes through the horizontal (in rad $$s^{-1}$$) will be ($$g = 10 ms^{-2}$$)
1329987_e0b0a2a584224bb68881b29459656dc2.png
  • $$\sqrt{30}$$
  • $$\sqrt{\dfrac{30}{2}}$$
  • $$\dfrac{\sqrt{30}}{2}$$
  • $$\dfrac{\sqrt{20}}{3}$$
The phase space diagram for a ball thrown vertically up from ground is

28721_46bc9d3e999e454d8a6ad35355964bd6.png
The force 'F' acting on a particle of mass 'm' is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is
312758.png
  • 24 Ns
  • 20 Ns
  • 12 Ns
  • 6 Ns
The reading of a spring balance corresponds to $$100$$N while situated at the north pole and a body is kept on it. The weight record on the same scale if it is shifted to the equator, is(take, $$g=10m/s^2$$) and radius of the earth, $$(R=6.4\times 10^3m$$).
  • $$99.66$$N
  • $$110$$N
  • $$9766$$N
  • $$106$$N
Two spheres of same size one of mass $$2 kg$$ and another of mass $$4 kg$$ are dropped simultaneously from the top of Qutab Minar (height $$= 72   m$$). When they are $$1 m$$ above the ground, the two spheres have the same:
  • momentum
  • kinetic energy
  • potential energy
  • acceleration
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
A thin rod of length $$4l$$ and $$4m$$ is bent at the points as shown in figure. What is the moment of inertia of the rod about the axis passes through point $$O$$ and perpendicular to the plane of paper?
730981_d1811a9070884aff89c3a049397bcb52.jpg
  • $$\dfrac {Ml^{2}}{3}$$
  • $$\dfrac {10Ml^{2}}{3}$$
  • $$\dfrac {Ml^{2}}{12}$$
  • $$\dfrac {Ml^{2}}{24}$$
Two rings of radius $$R$$ and $$nR$$ made of same material have the ratio of moment of inertia about an axis passing through centre in $$1 : 8$$. The value of $$n$$ is
  • $$2$$
  • $$\overline {2}$$
  • $$4$$
  • $$\dfrac {1}{2}$$
Consider the following two statements A and B and identify the correct choice
A) The torques produced by two forces of couple are opposite to each other
B) The direction of torque is always perpendicular to plane of rotation of body
  • A is true but B is false
  • A is false but B is true
  • Both A and B are true
  • Both A and B are false
The centre of a mass of a rigid body lies
  • inside the body
  • outside the body
  • neither $$(a)$$ nor $$(b)$$
  • either $$(a)$$ or $$(b)$$
Which of the following has the maximum momentum?
  • A 100 kg vehicles moving at 0.02 ms$$^{-1}$$.
  • A 4 g weight moving at 10,000 cms$$^{-1}$$.
  • A 200 g weight moving with kinetic energy of 10$$^{-6}J$$.
  • A 20 g weight after falling one kilometer.
Equal volume of two solution having pH = 2 and pH = 10 are mixed together at 90C. Then pH of resulting solution is : (Take Kw at 90C = $$10^{-12}$$)
  • 2 + log 2
  • 10 log 2
  • 7
  • 6
When the velocity of a body is doubled
  • kinetic energy is doubled
  • acceleration is doubled.
  • momentum is doubled.
  • potential energy is doubled.
The centre of gravity depends on the acceleration due to gravity at the given place.
  • True
  • False
Which of the following pairs of physical quantities are not analogous to each other in case of translatory motion and rotational motion, 
  • force, torque
  • mass, moment of inertia
  • couple, torque
  • linear momentum, angular momentum
The motion of centre of mass depends on 
  • total external forces
  • total internal forces
  • sum of $$(a)$$ and $$(b)$$
  • None of these
A body of mass 5 kg undergoes a change in speed from 20 to 0.20 m/s. The momentum of the body would
  • increase by 99 kg m/s
  • decrease by 99 kg m/s
  • increase by 101 kg m/s
  • decrease by 90 kg m/s
State whether given statement is True or False.
Centre of gravity of a freely suspended body always lies vertically below the point of suspension.
  • True
  • False
Can the centre of gravity be situated outside the material of the body ?
  • Yes
  • No
  • Can't say
  • None
On doubling the speed of of an object its:
  • K.E is doubled
  • P.E is doubled
  • Momentum is doubled
  • Acceleration is doubled
A stick is thrown in the air and lands on the ground at some distance from the thrower. The centre of mass of the stick will move along a parabolic path
  • in all cases
  • only if the stick is uniform
  • only if the stick has linear motion but no rotational motion
  • only if the stick has a shape such that its centre of mass is located at some point on it and not outside it
If the resultant of all external forces is zero, then velocity of centre of mass will be
  • zero
  • constant
  • either $$(a)$$ or $$(b)$$
  • neither $$(a)$$ nor $$(b)$$
State whether true or false :
The position of centre of gravity of a body remains unchanged even when the body is deformed. 
  • True
  • False
  • Ambiguous
  • Data insufficient
A body of mass 5 kg undergoes a change in speed from 20 to 0.20 m/s. The momentum of the body would :
  • increase by 99 kg m/s
  • decrease by 99 kg m/s
  • increase by 101 kg m/s
  • decrease by 101 kg m/s
Where should be the centre of gravity of a body ?
  • It must lie within the body
  • It may be near but not essentially within the body
  • It changes its position from time to time
  • It must be outside the body
Two particles A and B initially at rest move towards each other under a mutual force of attraction. The speed of centre of mass at the instant when the speed of A is v and the speed of B is 2v is 
  • v
  • Zero
  • 2 v
  • 3 v/2
The ratio of the radii of gyration of a circular disc to that of a circular ring, each of same mass and radius, around their respective axis is :
  • $$\sqrt{3} :\sqrt {2}$$
  • $$1 :\sqrt {2}$$
  • $$\sqrt{3} : 1$$
  • $$\sqrt{5} :\sqrt {3}$$
State whether true or false.
Moon revolving around the earth exhibits rotatory and Periodic motion.
  • True
  • False
A bullet of mass $$A$$ and velocity $$B$$ is fired into a block of wood of mass $$C$$. If loss of any mass and friction be neglected, the velocity of the system must be
  • $$\displaystyle\frac{AB}{A + C}$$
  • $$\displaystyle\frac{A + C}{B + C}$$
  • $$\displaystyle\frac{AC}{B + C}$$
  • $$\displaystyle\frac{A + B}{AC}$$
An object moving with kinetic energy $$KE = 100 J$$ and momentum $$p=50 kg  {m}/{s}$$. Find out the mass of the moving object?
  • $$2 kg$$
  • $$4 kg$$
  • $$6.25 kg$$
  • $$12.5 kg$$
  • $$25 kg$$
Which of the following statements can be suitable?
  • Rotational motion is a type of circular motion.
  • Circular motion is similar to rotational motion.
  • Rotational and circular motion are fundamentally unrelated.
  • None of these
Blades of a moving fan exhibit :
  • Rotatory motion
  • Linear motion
  • Projectile motion
  • Curvilinear motion
A potter's wheel executes which type of motion?
  • Rotatory Motion
  • Curvilinear motion
  • Linear motion
  • Projectile motion
Rolling of ball on the ground is the instance of __________ as well as ____________
  • Periodic motion, rotational motion
  • Oscillatory motion, rotational motion
  • Curvilinear motion, rotational motion
  • Rectilinear motion, rotational motion
A truck is moving with the speed of $$20 {m}/{s}$$ and having a momentum of $$12,000$$ $$kg$$ $${m}/{s}$$. Find out the mass of the truck ?
  • $$240,000 kg$$
  • $$6,000 kg$$
  • $$1,200 kg$$
  • $$600 kg$$
  • $$120 kg$$
A disc is rotating with an angular speed of $$\omega$$. If a child sits on it which of the following is conserved?
  • Kinetic energy
  • Potential energy
  • Linear momentum
  • Angular momentum
If you place pivot at center of a meter rule, weight has no
  • property
  • Concern
  • Turning effect
  • Magnitude
Reference to ability of an object to return to its original position after it has been tilted slightly is termed as:
  • Stability
  • Equilibrium
  • Centre of gravity
  • Torque
The moment of inertia of a disc of radius 0.5 m about its geometric axis is 2 kg-$$m^2$$. If a string is tied to its circumference and a force of 10 Newton is applied, the value of torque with respect to this axis will be :-
  • 2.5 N-m
  • 5 N-m
  • 10 N-m
  • 20 N-m
The apparent weight of a body is :
  • may be positive
  • may be negative
  • may be zero
  • is always positive
Which is the only vector quantity out of the following?
  • Charge of a gold leaf electroscope
  • Electrostatic potential
  • Current flowing in a metal
  • Angular momentum of a spinning body
Radius of gyration of a thin uniform rod of mass M length L about an axis perpendicular to it at one of its ends is:
  • $$L$$
  • $$L/2$$
  • $$L/ 2 \sqrt(3)$$
  • $$L/\sqrt(3)$$
Angular momentum and angular velocity for a rolling sphere of radius R are related by the formula
  • $$L = I\omega$$; I is the moment of inertia of the sphere
  • $$L = I\omega^2$$ I is the moment of inertia of the sphere
  • $$L = \dfrac{I}{\omega}$$, I is the moment of inertia of the sphere
  • $$L = I\omega-f \times R$$; f is the frictional force and R is the radius of the sphere and I is the moment of inertia of the sphere
Four thin uniform rods each of length L and mass M are joined to dorm a square. The moment of inertia of square about an axis along its one diagonal is then
  • $$\dfrac{mL^2}{6}$$
  • $$\dfrac{2}{3}mL^2$$
  • $$\dfrac{3 mL^2}{4}$$
  • $$\dfrac{4 mL^2}{3}$$

The momentum P and kinetic energy E of a body of mass m are related as :
  • $$P = \sqrt {2mE} $$
  • $$P = \dfrac{1}{2}mE$$
  • $$P = \dfrac{{2m}}{E}$$
  • $$P=2mE$$
If the kinetic energy of a body increases by $$0.1\%$$, the percent increase of its momentum will be ......
  • $$0.05\%$$
  • $$0.1\%$$
  • $$1.0\%$$
  • $$10\%$$
A $$0.5\ kg$$ ball moving with a speed of $$12m/s$$ strikes a hard wall and return back with same velocity. Find change in momentum.
  • 12 kg m/s
  • 20 kg m/s
  • 22 kg m/s
  • 120 kg m/s
A body has its centre of mass at the origin. The x-coordinates of the particles 
  • may be all positive
  • must be positive for some particles and negative in other particles
  • Must be all non - negative
  • may be positive for some particles and negative in other particles
Linear velocity of first sphere after it again starts rolling without slipping is-
  • $$\dfrac{2}{5} R\omega$$
  • $$\dfrac{2}{7} R\omega$$
  • $$\dfrac{7}{10} R\omega$$
  • $$\dfrac{7}{5} R\omega$$
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