CBSE Questions for Class 11 Engineering Physics Laws Of Motion Quiz 7 - MCQExams.com

A particle of mass m strikes a wall with speed v at an angle $$30^0$$ with the wall elastically as shown in the figure. The magnitude of impulse imparted to the ball by the wall is :
769745_c4a3b2ca2f894cdab341f67a1990f7fd.png
  • mv
  • $$\dfrac{mv}{2}$$
  • 2mv
  • $$\sqrt{3}$$ mv
Two people push a car for 3 sec, with a combined net force of 200 N.The impulse provided to the car............
  • 400 N-sec.
  • 500 N-sec.
  • 600 N-sec.
  • 300 N-sec.
A simple pendulum with bob of mass $$m$$ and length $$x$$ is held in position at an angle $$1$$ and then angle $$2$$ with the vertical. When released from these positions, speeds with which it passes the lowest positions are $${v}_{1}$$ and $${v}_{2}$$ respectively. Then, $$\cfrac { { v }_{ 1 } }{ { v }_{ 2 } } $$ is 
  • $$\cfrac { 1-\cos { { \theta }_{ 1 } } }{ 1-\cos { { \theta }_{ 2 } } } $$
  • $$\sqrt { \cfrac { 1-\cos { { \theta }_{ 1 } } }{ 1-\cos { { \theta }_{ 2 } } } } $$
  • $$\sqrt { \cfrac { 2gx(1-\cos { { \theta }_{ 1 } } ) }{ 1-\cos { { \theta }_{ 2 } } } } $$
  • $$\sqrt { \cfrac { 1-\cos { { \theta }_{ 1 } } }{ 2gx(1-\cos { { \theta }_{ 2 } } ) } } $$
If n balls hit elastically and normally on a surface per unit area and all units has mass m and are moving with same velocity u, then force on surface is: 
  • $$mun$$
  • $$2mun$$
  • $$\dfrac{1}{2}mu^2n$$
  • $$mu^2n$$
A bullet is fired from a gun. The force on the bullet is given by $$F = 600 - 2\times 10^{5}t$$, where $$F$$ is in newtons and $$t$$ in seconds. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to the bullet?
  • $$9\ Ns$$
  • Zero
  • $$0.9\ Ns$$
  • $$1.8\ Ns$$
A curved road of diameter $$1.8\ km$$ is banked so that no friction is required at a speed of $$30\ m/s$$. What is the banking angle?
  • $$6^{\circ}$$
  • $$16^{\circ}$$
  • $$26^{\circ}$$
  • $$0.6^{\circ}$$
A $$1$$m long uniform beam is being balanced as shown in the given figure. What are the forces X and Y?
809931_4f9cd6905c5442e4be123d4ff24f1d8a.jpg
  • Force X-$$1$$N, Force Y-$$0$$N
  • Force X-$$2$$N, Force Y-$$1$$N
  • Force X-$$3$$N, Force Y-$$3$$N
  • Force X-$$4$$N, Force Y-$$7$$N
A particle is projected so as to just move along a vertical circle of radius $$r$$ with the help of the massless string. The ratio of the tension in the string when the particle is at the lowest and highest point on the circle is?
  • $$1$$
  • Finite but large
  • Zero
  • Infinite
A solid sphere is placed on a smooth horizontal plane. A horizontal impluse $$I$$ is applied at a distance $$h$$ above the central line as shown in the figure. Soon after giving the impulse the sphere starts rolling.
The ratio $$h/R$$ would be
774350_8fe35357de394f0cb37a6ddfa013521f.png
  • $$\dfrac {1}{2}$$
  • $$\dfrac {2}{5}$$
  • $$\dfrac {1}{4}$$
  • $$\dfrac {1}{5}$$
A car sometimes overturns while taking a turn. When it overturns, it is
  • The inner wheel which leaves the ground first
  • The outer wheel which leaves the ground first
  • Both the wheels leaves the ground simultaneously
  • Either wheel which leaves the ground first
A railway track is banked for a speed v, by making the height of the outer rail h higher than that of the inner rail. The distance between the rails is d. The radius of curvature of the track is r. Then, 
  • $$\dfrac{h}{d}=\dfrac{v^2}{rg}$$
  • $$tan(sin^{-1}\dfrac{h}{d})=\dfrac{v^2}{rg}$$
  • $$tan^{-1}(\dfrac{h}{d})=\dfrac{v^2}{rg}$$
  • $$\dfrac{h}{r}=\dfrac{v^2}{dg}$$
"To every action, there is equal and opposite reaction". It is Newton's
  • First Law
  • Second Law
  • Third Law of Motion
  • None of these
A simple pendulum of length $$L$$ carries a bob of mass $$m$$. When the bob is at its lowest position, it is given the minimum horizontal speed necessary for it to move in a vertical circle about the point of suspension. When the string is horizontal the net force on the bob is:
  • $$\sqrt { 10 } mg$$
  • $$\sqrt { 5 } mg$$
  • $$4mg$$
  • $$1mg$$
The term inertia was first used by
  • Newton
  • Galileo
  • Aristotle
  • Kepler
A rigid ball of mass m strikes a rigid wall at $$60^0$$ and gets reflected without loss of speed as shown in the figure. The value of impulse imparted by the wall on the ball will be:
939483_9dd65dd4862b4ad184f91f4796537150.png
  • mV
  • 2 mV
  • $$\dfrac{mV}{2}$$
  • $$\dfrac{mV}{3}$$
A girl presses her physics textbook against a rough vertical wall with her hand. The direction of the frictional force on the book exerted by the wall is:
  • Downwards
  • Upwards
  • Out from the wall
  • Into the wall
If a car is moving at a velocity $$v$$ in a circular road with coefficient of friction $$\mu$$ and banking angle $$\theta$$. Find the radius of the road such that friction force doesn't act on the car in the radial direction.
  • $$r=\dfrac{v^2}{g\tan \theta}$$
  • $$r = \dfrac{\sqrt{v}}{g\tan \theta}$$
  • $$r = \sqrt{\dfrac{v^2}{g\tan \theta}}$$
  • $$r=\dfrac{v^2}{\sqrt{g}}$$
A car is moving on a frictionless (in the radial direction) circular banked road, with a banking angle of $$15^o$$, find the velocity of the car.
Mass of car is $$600\ kg$$, the radius of the circular road $$=10m$$ 
Assume $$g=9.81\ m/s^2$$
  • 4.26 m/s
  • 5.12 m/s
  • 51.2 m/s
  • 42.6 m/s
A ball of mass m strikes a rigid wall with speed u and rebounds with the same speed. The impulse imparted to the ball by the wall is:
  • 2mu
  • mu
  • Zero
  • -2mu
A particle is tied to one end of a light inextensible string and is moved in a vertical circle, the other end of the string is fixed at the centre. Then for a complete motion in a circle, which is correct.
(air resistance is negligible).
  • Acceleration of the particle is directed towards the centre
  • Total mechanical energy of the particle and earth remains constant
  • Tension in the string remains constant
  • Acceleration of the particle remains constant
A house is on built on the top of a hill with $$45^0$$ slope. Due to the sliding of material and sand from top to the bottom of hill, the slope angle has been reduced.
If the coefficient of static friction between sand particles is 0.75, what is the final angle attained by hill? ($$ tan^{-1}0.75 = 37^0$$)
987189_a37e9b0ed25444e1832a1b0eebf7b46a.png
  • $$8^0$$
  • $$45^0$$
  • $$37^0$$
  • $$30^0$$
A box of mass 8 kg is placed on a rough inclined plane of inclined $$\theta$$. Its downward motion can be prevented by applying an upward pully F and it can be made to slide upwards by applying a force 2F. The coefficient of friction between the box and the inclined plane is
  • $$(tan\theta)/3$$
  • $$tan\theta$$
  • $$(tan\theta)/2$$
  • $$2tan\theta$$
Two wires $$AC$$ and $$BC$$ are tied at $$C$$ of a small sphere of mass $$5\ kg$$, which revolves at a constant speed $$v$$ in the horizontal plane with the speed $$v$$ of radius $$1.6\ m$$. Find the minimum value of $$v$$.
987320_03c2ec504f0f40f49da1331d19c90e9a.png
  • $$4\ m{s}^{-1}$$
  • $$2\ m{s}^{-1}$$
  • $$2.5\ m{s}^{-1}$$
  • None of these
A particle of mass $$m$$ slides on a frictionless surface ABCD, starting from rest as shown in Figure. The part BCD is a circular arc. If it loses contact at point P, the maximum height attained by the particle from point C is :
984147_0f825436d17b4a04887158269b442eee.png
  • $$R[2 +\dfrac{1}{2\sqrt{2}}]$$
  • $$R[2 +\dfrac{1}{2\sqrt{2}}]R$$
  • $$3R$$
  • None of these
A block of mass m rests on a rough inclined plane. The coefficient of friction between the surface and the block if $$\mu$$. At what angle of inclination $$\theta$$ of the plane to the horizontal will the block just start to slide down the plane?
  • $$\theta=tan^{-1}\mu$$
  • $$\theta=cos^{-1}\mu$$
  • $$\theta=sin^{-1}\mu$$
  • $$\theta=sec^{-1}\mu$$
The velocity of a body moving in a vertical circle of radius r is $$\sqrt{7gr}$$ at the lowest point of the circle. What is the ratio of maximum and minimum tension?
  • $$4: 1$$
  • $$\sqrt 7:1$$
  • $$3: 1$$
  • $$2: 1$$
Fig A.43 show three block on a rough surface under the influence of a force $$P$$ of the same magnitude in all the three cases. 
Co0efficient of friction is the same between each block and the ground. What possible relation holds between the magnitude of normal 
reaction and friction forces? (Assume that the block do not overturn about edge.) Here, $${ f }_{ A }$$,$$ { f }_{ B }$$ and $${ f }_{ 
C }$$ are frictional forces and $$ { N }_{ A }$$, $$ { N }_{ B }$$ and $$ { N }_{ C }$$ are reactions.

987456_764e9703f0b74dc3b8064e138107e50d.png
  • $${ N }_{ A }\ >\ { N }_{ C }\ >\ { N }_{ B }$$
  • $${ f }_{ A }\ >\ { f }_{ C }\ >\ { f }_{ B }$$
  • $${ f }_{ C }\ >\ { f }_{ A }\ =\ { f }_{ B }$$
  • $${ N }_{ C }\ >\ { N }_{ A }\ =\ { N }_{ B }$$
For the conditions of the equilibrium of the body, i.e. the rigid body only the external forces defines the equilibrium. Because the internal forces cancels out so not to be considered.
  • The first part of the statement is false and other part is true
  • The first part of the statement is false and other part is false too
  • The first part of the statement is true and other part is false
  • The first part of the statement is true and other part is true too
A man revolves a stone of mass m tied to the end of a string in a vertical circle of radius R, The net force at the lowest and height points of the circle directed vertical downwards are 
Here $$T_1, T_2$$ and  $$v_1, v_2$$ denote the tension in the string and the speed of the stone at the lowest and highest points, respectively.
  • Lowest point: $$mg - T_1$$ Highest point : $$mg + T_2$$
  • Lowest point: $$mg + T_1$$ Highest point : $$mg - T_2$$
  • Lowest point: $$mg + T_1 -\frac{mv^2}{R}$$ Highest point: $$mg - T_2 +\frac{mv^2}{r}$$
  • Lowest point: $$mg - T_1 -\frac{mv^2}{R}$$ Highest point: $$mg + T +\frac{mv^2}{r}$$
A box of mass m is made to move from A to B as shown in figure. Where will the normal force be larger:
1005592_9adba6daf6194c86aaaec9334848ce28.PNG
  • A
  • B
  • Same at both A and B
  • None of the above
Complete the statement of the first law of motion. "A body at rest stays at ____ and a body in motion stays in ____ unless an ____ is applied" 
  • Motion; Rest; External Force
  • Rest; Motion; External Force
  • Rest; Motion; Internal Force
  • None of these
A ball is moving in the direction as shown. What will be the direction of momentum?
1005902_3809ea0c2d6e4c58aae24c47c1a45763.png
  • $$W$$
  • $$N$$
  • $$S$$
  • $$E$$
Which of the following is correct?
  • The application of the conditions of the equilibrium of the body is valid only in the 2D
  • The application of the conditions of the equilibrium of the body is valid only in the 3D
  • The application of the conditions of the equilibrium of the body is valid only in the 1D
  • The application of the conditions of the equilibrium of the body is valid throughout
A particle of mass 1 kg is suspended by means of a string of length L=2 m. The string makes $$6/\pi$$ rps around a vertical axis through the fixed end. The tension in the string is
  • 72 N
  • 36 N
  • 288 N
  • 10 N
A 0.25kg ball attached to a 1.5 m rope moves with a constant speed of 15 m/s around a vertical circle. Calculate the tension force on the rope at the middle of the circle:
  • 37.5 N
  • 137.5 N
  • 2.5 N
  • 25 N
A mass attached to a string that is itself attached to the ceiling swings back and forth. If the bob is observed to be moving upward at a given instance, as shown to the right, which arrow best depicts the direction of the net force acting on the bob at that instant
1004868_45bb52a2d04041709d1dadbd2a9924ad.PNG
  • A
  • B
  • C
  • D
Two blocks of same mass ($$4$$kg) are placed according to diagram. Initial velocities of bodies are $$4$$ m/s and $$2$$ m/s and the string is taut. Find the impulse on $$4$$ kg when the string again becomes taut.
993213_cd6d35e4ea914bee9be41a16a14d49e6.png
  • $$24$$ N-s
  • $$6$$ N-s
  • $$4$$ N-s
  • $$2$$ N-s
Momentum of an object changes from $$5\ kg\ m/s$$ to $$15\ kg\ m/s$$ in $$2$$ seconds. What is the force applied on the object?  
  • $$10\ N$$
  • $$5\ N$$
  • $$20\ N$$
  • $$40\ N$$
A football player kicks a $$0.25kg$$ ball and imparts it a velocity of $$10m/s$$. The contact between foot and the ball is only $$\cfrac{1}{50}$$th of a second. The kicking force is
  • $$250N$$
  • $$125N$$
  • $$0N$$
  • $$3.78N$$
A weightless thread can bear tension up to $$30N$$. A stone of mass $$500\ g$$ is tied to it and revolved in a circular path of radius $$2m$$ in a vertical plane. If $$g=10{ms}^{-2}$$, then the maximum angular velocity of the stone will be:
  • $$2\ rad\ {s}^{-1}$$
  • $$5\ rad\ {s}^{-1}$$
  • $$8\ rad\ {s}^{-1}$$
  • $$16\ rad\ {s}^{-1}$$
Banking of roads is done due to
  • provide enough friction for circular motion of the vehicle
  • provide necessary centripetal force required for circular motion of the vehicle
  • provide enough radius of curvature for circular motion of the vehicle
  • provide enough area for navigating in the circular motion of the vehicle
The figure shows the position -time (x- t) graph of one-dimensional motion of a body of mass $$0.4$$ kg. The magnitude of each impulse is :
1011505_60e8607972b1481b85d380089dd69b80.png
  • $$0.4$$ Ns
  • $$0.8$$ Ns
  • $$1.6$$ Ns
  • $$0.2$$ Ns
Impulse of the force exerted by A and B during the collision, is equal to
1014503_e4abb3e6496240429a948a8145f122e4.PNG
  • $$\left( \sqrt { 3 } mi+3mj \right) kg-m/s$$
  • $$\left( \cfrac { \sqrt { 3 } }{ 2 } mi-\sqrt { 3 } mj \right) kg-m/s$$
  • $$\left( 3mi-\sqrt { 3 } mj \right) kg-m/s$$
  • $$\left( 2\sqrt { 3 } mi+3mj \right) kg-m/s\quad $$
Though friction can provide necessary centripetal force, the banking of roads is considered as advantageous in highways:
  • True
  • False
A block of mass $$m$$ is on an inclined plane of angle of angle $$\theta$$. The coefficient of friction between the block and the plane is $$\mu$$ and $$\tan { \theta  } >\mu$$. The block is held stationary by applying a force $$P$$ parallel to the plane. The direction of force pointing up the plane is taken to be positive. As $$P$$ is varied from $${ P }_{ 1 }=mg\left( \sin { \theta  } -\mu \cos { \theta  }  \right)$$ to $${ P }_{ 2 }=mg\left( \sin { \theta  } -\mu \cos { \theta  }  \right)$$, the frictional force $$f$$ versus $$P$$ graph will look like
1010147_fffc8ca385bc4de5b58567f92d69d048.png
A vehicle is at rest on a banked road with angle of banking $$\theta$$. The normal reaction of the vehicle is $${N}_{1}$$. When the vehicle takes a turn on the same road the normal reaction is $${N}_{2}$$. Then $${N}_{1}/{N}_{2}$$ is equal to:
  • $$1$$
  • $$\sin ^{ 2 }{ \theta }$$
  • $$\cos ^{ 2 }{ \theta }$$
  • $$0.5 \sin (2\theta)$$
A cyclist leans with the horizontal at an angle of $$30^{o}$$, while negotiating round a circular road of radius $$20\sqrt{3}$$ meters. Speed of the cycle should be :
  • $$7\sqrt{3}\ m/s$$
  • $$14\ m/s$$
  • $$7\sqrt{6}\ m/s$$
  • $$14\sqrt{3}\ m/s$$
A weightless thread can support tension upto $$30N$$. A particle of mass $$0.5kg$$ is tied to it and is revolved in a circle of radius $$2m$$ in a vertical plane. If $$g=10m/{s}^{2}$$, then the maximum angular velocity of the stone will be
  • $$5rad/s$$
  • $$\sqrt{30}rad/s$$
  • $$\sqrt {60}rad/s$$
  • $$10rad/s$$
A car is moving in a circular horizontal track of radius $$10m$$ with a constant speed of $$10m/s$$. A plumb bob is suspended from the roof of the car by a light rigid rod of length $$1m$$. The angle made by the rod with track is
  • zero
  • $${30}^{o}$$
  • $${45}^{o}$$
  • $${60}^{o}$$
A road is $$8\ m$$ wide. Its radius of curvature is $$40\ m$$. The outer edge is above the lower edge by  distance of $$1.2\ m$$. The most suited velocity on the road is nearly:
  • $$5.7\ ms^{-1}$$
  • $$8\ ms^{-1}$$
  • $$36.1\ ms^{-1}$$
  • $$9.7\ ms^{-1}$$
0:0:1


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