Newton's law of motion Questions and Answers

Two blocks A and B of masses 2 kg and 8 kg respectively are kept in contact and pressed against a rough vertical wall by applying a horizontal force F 50 N as shown The frictional force acting between the two blocks is A zero B 6N C 8 N D 10 N 50N F A 2 kg H 0 3 H 0 2 B 8 kg 0 7 0 6

An open train car with a mass of 21902190 kg coasts along a horizontal track at the speed 3 013 01 m s The car passes under a loading chute and as it does so gravel falls vertically into it for 3 373 37 s at the rate of 439439 kg s What is the car s speed vfvf after the loading is completed Ignore rolling friction

In shown system strings and pulley are frictionless and massless Block A is moving downward with velocity of 7m s which is increasing at a rate of 2 m s while block C is moving upward with a velocity of 9 m s which is decreasing at a rate of 3 m s The block B is moving downward with velocity of VB m s which is decreasing at a rate of ag m s Find the value of v l el 99

Two blocks A and Beach of mass kg are connected by a massless inextensible string and kept on horizontal surface Coefficient of friction between block and surface is shown in figure A force where k 1 N s and this time in second applied on A Then g 10 m s F kt B 14 0 2 44 0 2 A 14 0 2 H 0 4 mum work done by friction force on block B is zero in time interval t 0 to t 3s work done by friction force on block A is zero in time interval t 0 to t 3s work done by tension on Bis also zero in time interval t 0 to t 3s speed of blocks at t 10s is 27 5 m s

While standing in an elevator you see a screw fall from the ceilling of elevator The celling of elevator is 5 m above the floor of the elevator The elevator is moving upward with a constant speed of 4 m s How long does it take for the screw to hit the floor g 10 m sec

marks The system shown in the figure is initially at origin and is moving with a constant velocity 5m s k A force F 120t i acts on mass m2 here F is in Newton and time t is in seconds The man throws a light ball at instant when m starts slipping on m2 with a velocity 10 m s vertically up with respect to him self Taking the mass of each block and man as 60 kg and assuming that the man never slips on m The coefficient of fric between m and m is 0 2 There is no friction between m and ground Neglect the dimensions of the system The time at which man throws the ball is 3 sec y A I Projection velocity of ball with respect to ground is 31 10j 5k Projection velocity of ball with respect to ground is 1 5i 10j 5k OZ coordinate of the point where ball lands is 25 m I X man m m 0 2 Smooth Save

The system shown in the figure below consists of a light inextensible cord light frictionless pulleys and blocks of equal mass Notice that block B is attached to one of the pulleys The system is initially held at rest so that the blocks are at the same height above the ground The blocks are then released Find the speed of block A at the moment the vertical separation of the blocks is h Use any variable or symbol stated above along with the following as necessary g

solid sphere of mass 1 kg is tied with a light string to a smooth vertical wall as shown in ne figure A The normal reaction exerted by wall to sphere is 10 N 3 The normal reaction exerted by wall to sphere is 10 2 N C The tension in the string is 10N O The tension the string is 10 2 N

There are three block A B and C of mass 1 kg 2 kg and 3 kg are shown in figure If 15 and 6 N force apply on A and C block Assume surface is smooth 25 26 15 N A 1 kg Find the acceleration of system 3 A m s along east 2 C m s along east 3 B 2 kg C 3 kg 6 N 3 B m s along west D m s along west 2 m s 3 Find the ratio of normal force b w A and B to normal force b w B and C 7 9 6 2

angle 80 A particle is fired with with the horizontal What is the magnitude of change in velocity when it returns to the ground 1 u cos 0 2 u 3 2u sin 0 4 u cos0 u 181 In the above the change in speed is 1 u cos 0 2 0 3 u sin 0 4 u cose u

In the given figure the coefficient of friction between 4kg and 5 kg blocks is 0 2 and between 5 kg block and ground is 0 1 respectively Choose the correct statements f4kg 5 kg 2 0 2 5 kg 0 1 1 Minimum force needed to cause system to move is 17 N 2 When force is 4N static friction at all surfaces is 4N to keep system at rest 3 Maximum acceleration of 4kg block is 2m s 4 Slipping between 4kg and 5 kg blocks start when F is 17N 1 fa fa 17 2 N fay Art HER F 3 4kgm s 4 F 17 N 4kg 75 kg FREM GR V I Q P 4kg 5kg mi

option without selecting any incorrect option second option in this case will result in t marks A 1 kg block is kept on L shaped block of mass 2 kg which is kept on horizontal surface as shown A force F 2N is applied on the massless string which is connected to 1 kg block Coefficient of friction between the blocks 0 1 There is no friction between 2 kg block and ground Pulley is massless and frictionless Choose the correct options s Acceleration of 1 kg block is 1 m s Acceleration of 2 kg block is 2 m s Acceleration of 2 kg block with respect to 1 kg block is 2 5 m s Net force on 2 kg block is 4 N 2kg F 2N 1kg Save

An elliptical smooth wire frame carries a bead of mass m and is moved along X axis in a vertical plane At equilibrium the co ordinates of the bead with respect to origin O may Y I 1 8 1 6 m O 1 8 1 6 m O 1 6 1 8 m 1 6 1 8 m m 2m 3m a 5 m s X

Find the time taken by block to reach bottom most point H 0 2 1 0 92 s 2 t t 2 3 2 9 8 2s a 9 8 a 0 2 2 0 2 4 9 1 79 3 1 2 2 E 200X 30 2 1 13 s 9 8 3 2 1 kg 5mC 1g sin30 REX 1m 3 2 1 s IN 1g cos30 LO 5 INST

Two particles A and B are connected by a rigid rod AB The rod slides along perpendicular rails as shown here The velocity of A to the left is 10 m s What is the velocity of B when angle a 60 a 10 m s c 5 8 m s b 9 8 m s d 17 3 m s 1998

marks A plank inclined at an angle of a to the horizontal lies on two supports A and B figure over which it can slip without friction under the action of its own weight Mg With what acceleration and in what direction should a me mass m move along the plank so that it should not slip the man should move down the plank the acceleration of the man should be g sin a the acceleration of the man should be g sin a the man should move up the plank 1 1 B Save

marks A string is wrapped round a log of wood and it is pulled with a constant force F as shown in the figure Tension in the string increases with increase in 8 Tension T in the string decreases with increase in 8 Tension T Fife m 3 Tension T Fife m 4 F

Pulleys P and P are smooth and fixed The light pulley P is moving upwards by applying a forc F of 120 N The pulley P is also light and movable Block A B and C of their respective masses kg 2 kg and 3 kg are initially placed at the smooth horizontal surface Then choose the correc options g 10 m s 7777 A The acceleration of block A is 50 m s B The acceleration of block B is 5 m s P2 C The acceleration of block C is zero D The pulley P has non zero acceleration P3 BC

In the arrangement shown in figure the mass of the wedge Mis 10 kg and the mass of the body mis 4 kg The coefficient of friction between wedge M and mass m is 0 5 There is no friction between wedge and horizontal surface Neglecting the masses of pulley and strings the acceleration of the wedge M in m s2 is Take g 10 m s M

80 railway wagons all of same mass 5 x 10 kg are pulled by an engine with a forc of 4 x 105 N The tension in the coupling between 30th and 31st wagon from th engine is A 25 x 104 N 1 B 20 104 N D 40 104 N To one of its ends a mass of 3kg C 32 104 N X

An observer with a mass 10kg moves at a constant velocity of 10 m s A constant force then acts for 4 seconds on the object and gives it a speed of 2m s in opposite direction The acceleration produced in it is A 3 m s B 3 m s C 0 3 m s D 0 3 m s

B 60 ms C 0 1 ms D 5 ms A force of 5N acts on a body of weight 9 8N What is the acceleration produced m sec D 0 51 A 49 B 5 C 1 46 Ram and Sam are pulling at the two ends of a rong with

A ball of mass m moves with speed v and it strikes normally with a wall and reflected back normally if its time of contact with wall is t then find force exerted by ball on wall 1 2mv t 3 mvt 2 mv t mv 2t

6 The figure shows the position time x t graph of one dimensional motion of a body of mass 0 4 kg It suffers impulse at regular intervals The magnitude of each impulse is 2 x m 2468 1 0 2 Ns 2 0 4 Ns 3 0 8 Ns 10 12 14 16 t s

A FireFighting Vehicle is moving with a certain velocity at speed V on a straight track The dimensions of the vehicle is 30 cm in length 20 cm in breadth and 30 cm in height The weight of vehicle is 3 KG in total including 1 liter of filled water tank The water cannon is spraying water at rate Q in the up and down direction Find a scientific relation in equation format so that vehicle maintains stability while moving and spraying water simultaneously V 2 30cm water cannon moving up down 30cm height

A hinged construction consists of three rhombi with equal sides The vertex A3 mo with velocity V to the right Then A Speed of A is V 3 C Speed of A2 is V 3 B Speed of A is 2V 3 D Speed of A is 2V 3

3 86 A block of mass mis attached with a massless spring of force constant The block is placed over a rough inclined surface for which the coefficient of friction is The minimum value of M required to move the block up the plane is Neglect mass of string and pulley and fnction in pulley A B 45 a Firars exes

Two blocks are placed at rest on a smooth fixed inclined plane A force Facts on block of mass m and is parallel to the inclined plane as shown in figure Both blocks move up the incline Then F 0 m i Draw free body diagram of block of mass m and block mass m i Find accelerations of block of mass m and block mass

Block A is placed on the horizontal surface while block B is on the inclined one The blocks are connected by a cord and coefficient of friction are indicated in the figure Solve for the magnitude and direction of force P which will cause impending motion Als find the tension if the cord attached to the blocks P 200 200N A f 0 2 450 f 0 3 200N B 300

Two blocks A and B of equal mass are connected by a light inextensible taut string passing over two light smooth pulleys fixed to the blocks The parts of the string not in contact with the pulleys are horizontal A horizontal force F is applied to the block A as shown There is no friction F m Ho D the acceleration of A wat 2 times VILL Which of the following is correct B m A the sum of rate of changes of momentum of A and B is less than the magnitude of F B the sum of rate of changes of momentum of A and B is equal to the magnitude of the F C the sum of rate of changes of momentum of A and B is greater than the magnitude of F D the sum of rate of changes of momentum of A and B cannot be determined

For the system shown in the figure the pul leys are light and frictionless The tension in the string will be T m 0 2 A mg sin e 3 1 C mg sin 0 m 3 B 2 12 D 2mg sin 0 mg sin 0

ng a Is it possible for the mot straight line so that its velocity increases while its acceleration decreases 1 No because if acceleration is decreasing the object will be slowing down 2 No because velocity and acceleration must always be in the same direction Yes an example would be a falling object near the surface of the moon 4 Yes an example would be a falling object in 3

Two blocks of mass m and 2 m are connected with a string which is passing over a pulley disc of mass m and radius R as shown in the figure If system is released from rest then acceleration of the block will be T m R T

The coefficient of static friction between the two blocks is 0 363 What is the minimum acceleration of block 1 so that block 2 does not fall A 6 ms C 18 ms 2 2 a B 12 ms D 27 ms

A lift of mass 1000 kg which is moving with acceleration of 1 m s in upward direction then the tension developed in string which is connected to lift is a 9800 N c 11 000 N b 10 800 N d 10 000 N 2002

Centre of Mass of a Gas An ideal gas of molar mass M is contained in a very tall cylindrical vessel in the uniform gravitational field in which free fall acceleration is g Assuming the gas temperature is T find the height at which centre of mass of gas is located sad all prish

Three particles having masses m 2m 3m respectively are attached by three springs constants k 2 k and 2k respectively as shown find out accelearatiob of each block ju st after cutting from A B C D E an d F as shown in figure retched If the 4 what will be the an acceleration e block A on t

24 force should act on the body at an angle 30 to the horizontal so that the body just begins to move 25 3 A body of mass 0 1 kg is pressed against a wall with a horizontal force 5 N If coefficient of friction is 0 5 then find force of friction TL US N MS 3x253 ico with a velocity of 8 m s comes to rest after travelling 40 m Find the coefficient of

A boy of mass m standing on a block of mass M which in turn lying on a rough surface of coefficient of static friction Boy is pulling him through pulley system shown in the figure The maximum force he can exert so that block does not slip 1 m M m g 2 l M m9 mM M m g 1 4 4 M m g 1 u

ater ent s A A powerful man pushes a wall and the wall gets deformed The magnitude of force exerted E the wall on man will be equal to the magnitude of force exerted by man on the wall B Ten person are pulling horizontally an object on a smooth horizontal surface in differe directions The resultant acceleration of the object is zero Then the pull of each man is equal to the resultant pull of the other nine men C A massless object cannot exert force on any other object D All contact forces are electromagnetic in nature

2 5 Having gone through a plank of thickness h a bull changed its velocity vo Find the time of motion of the bullet the plank assuming the resistance force to be proportional the square of the velocity Ans h vo v vorloge 1

99 A body of mass 1kg is moving in the upwar direction with an acceleration of 2m s Calculat the work done by tension in first second at t C u 0 1 10 Joule 3 24 Joule AT 1kg 2m s 2 12 Joule 1 20

An a particle of mass m suffers one dimensional elastic collision with a nucleus at rest of unknown mass It is scattered directly backwards losing 64 of its initial kinetic energy The mass of the nucleus is 2019 Main 12 Jan II

jective Questions rce A high speed car and an innocent insect have a head on collision The the poor insect over the windshield Is the corresponding force that the insect exerts against the windshield greater less or the same Is the retardation of the car greater than less than or the same as that of the insect fixed and of balance B is attached

4 81 A spring of free length 15 cm is connected to the two masses as shown in the figure 4 149 and compressed 5 cm The system is released on a smooth horizontal surface Find the speed of each block when the spring is again at its fre length The force constant for spring is 2100 Nm 2 kg 3 kg 1 k Hrrrrrrrrrrrrr Ans 1 575 m s 1 05 m s Figure 4 149 2

41 A block of mass 20 kg is acted upon by a force F 30 N at an angle 53 with the horizontal in downward direction as shown in diagram The coefficient of friction between the block and the horizontal surface is 0 2 The friction force acting on the block by the ground is g 10 m s 1 40 0 N 3 18 0 N F 53 20 Kg TE 2 30 0 N 4 44 8 N

33 An object dropped from the top of a tower covers in the last second seven times the distance it covered in the first second Find the time of flight 1 2 s 2 3 s 3 4 s 4 5 s

3 E m To keep the mass from accelerating a spring is attached What is the minimum spring constant of the spring to keep th block from sliding if it extends x 0 12 m from its unstretched length N m Submit

A boy is standing on a weighing machine inside a lift When the lift goes upwards g with acceleration the machine shows the reading 50 kg wt When the lift goes 4 downward with acceleration the reading of the machine in kg wt would be

21 22 Find out mechanical advantage in given figure 1 4 3 2 1 W 2 3 4 1 A boy sitting on the topmost berth in the 21 fagfiffy 22 1 4 3 2 S W 2 3 4 1