Newton's law of motion Questions and Answers

sition X B A 30 60 D 60 4 Zero C The correct ascending order of magnitude impulse at points A B C D is 1 A B C D time 2 A B C D

6 4kg 1 4 4 Consider three cases in equilibrium 60 60 Kg 4kg 60 Kg 4kg 111 60 K A man of mass 60 kg is holding the string connected to block of mass 4kg as shown Ther the incorrect statement is 1 Normal reaction will be maximum on man in first case 2 Normal reaction will be least in third case 3 Tension in the string held by man is least in third case 4 Tension in string held by man is maximum in second case

A block of mass 5 kg is suspended by two light strings 1 and 2 as shown in figure If T and T2 be tension in strings 1 and 2 respectively then the value of T T2 is g 10 m s 30 50 N O 30 N O 28 N 5 kg 60

36 1 7777 F 3 of static friction is always more than the coefficient of kinetic friction A block of mass m is placed at rest on a rough horizontal surface with the coefficient of friction u The following figure shows four different ways in which a constant force F may be applied on the block Identify the situation in which the block can be moved with the least effort m m F 7777 2 T 4 m m F

In the given arrangement all strings and pulleys are ideal When system was released it was observed that m1 m2 do not move Then 5 1 m1 m3 m1m4 4m3 M4 3 m2 m3 m3m4 2m3 M4 M1 m m3 M4 2 m2 m3 m2m4 2 m m4 4 m1 m3 m1m4 8 m m4 Space for Rough Work

2 10 m s 4 10 m s 3 15 m s A lift coming from 8th floor is just about to 4th floor and stops on 4th floor Taking as origin and taking upward direction as p for all quantities which of following is c 1 x 0 v 0 a 0 2 x 0 v 0 a 0 3 x 0 v 0 a 0

Each of the figures below shows 3 blocks of masses 4m 3m and 2m acted on by an external horizon force F For each figure which of the following options is INCORRECT FAB Magnitude of the fo that block A exerts on block B FBC Magnitude of the force that block B exerts on block C Assu that the surface on which the blocks move is frictionless F 1 In figure 1 FAB 3 In figure 2 F AB 5F 9 4F 4m B 3m 2m Figure 1 4m B 3m 2m Figure 2 2 In figure 1 F 4 In figure 2 2F BC 9 Fac BC 5F F

Three blocks A B C are connected by two strings x y as shown in figure 1 9Kg 4Kg 1 9Kg A 0 1kg X B 0 1kg y t C 2m F Smooth 2m The system is pulled in right direction by force F If breaking strength of strings x y are 10 respectively then maximum value of F for which none of strings will breaks is 2 440N 1 400N 3 300N 4 330N

12 A plastic ball is suspended inside liquid filled in a closed cylindrical container shown in figure The elongation in spring is 1 mm The cylinder is now rotated about vertical axis shown with angular velocity o Assuming that length of spring b a elongation in spring will be 0 A 1 7 mm B 2 mm a C 1 mm D 1 4 mm a

3 Acceleration of 1 w r t rope is 5g upwards Find acceleration of 2 w r t rope so that block remains at rest 113 2 m

Three blocks of masses m m and m are connected by a massless string as shown The are pulling with a force F 40 N If m 10kg m 6kg and m 4kg then tension 7 and 7 will be A 10 N m B 20 N 10 12203 C 32 N D 40 N

Q A particle moving with velocity is acted by three forces shown by the vector triangle PQR The velocity of particle will NEET 2019 a Remain constant b Change according to the smallest force QR c Increase d decrease P R

Consider the infinite Atwood s machine shown below A string passes over each pulley with one end attached to a mass and the other end attached to another pulley All the masses are equal to m and all the pulleys and strings are massless The masses are held fixed and then simultaneously released What is the acceleration of the top mass m m

g 9 8 m s A body is thrown vertically upwards with a velocity of 49 m s Find the time that passes between the instants when it goes past a point 100 m from the ground in its upward and downward journey g 9 8 m s 4 28 s

A wire elongates by mm when a load W is 5 hanged from it If the wire goes over a pulley and two weights W each are hung at the two ends the elongation of the wire will be in mm 1 l 2 20 3 zero 4 1 2

A ball of m 1kg is connected from a spring of force constant 225 N m and another ball of mass 3m is hanging from it with the help of thread The system is in equilibrium now the thread is burned The maximum speed of mass m during the subsequent motion is vo Write the value of vo in OMR sheet EN

Two forces of same magnitude act on an isolated body in opposite directions to keep it at equilibrium position is this true according to Newton s third law

E OF FORCES NEWTON S THIRD LAW FREE BODY DIAGRAM An object of 5 kg is far away from the surface of the earth and has an acceleration of 6 m s towards t center of earth Find the force exerted by the object on the earth

Sir why the solution given in the book is a b c d since ther e is a force Ncostheta on wedge which will produce an acc eleration in the wedge since no 9 Wedge shown in the figure is fixed Syner force is acting on it is released from rest Neglect friction 1 Acceleration of block is M msine g M m Mgm 1 sin M m 2 Tension in the spring is 3 Net force on pulley is zero 4 Net force on wedge is zero M

The figure below shows Atwood s machine in which two containers are connected by a cord of negligible mass passing over a frictionless pulley also of negligible mass At time t 0 container 1 has mass 1 30 kg and container 2 has mass 3 16 kg but container 1 is losing mass through a leak at the constant rate of 0 274 kg s IN a At what rate is the acceleration magnitude of the containers changing at t 0 3 4849 x m s b At what rate is the acceleration magnitude of the containers changing at t 3 00 s 7 7948 x m s c When does the acceleration reach its maximum value Draw a free body diagram for container 1 and another one for container 2 Write Newton s second law for container 1 and also for container 2 The upward force on each is the same pull from the rope Assume container 2 accelerates down the y avis container 1 has the same magnitude of acceleration Once acceleration is determined in terms of m differentiate the expression with respect to time

block of mass m 4 50 kg on a frictionless inclined plane of angle 30 0 is connected by a cord over a massless frictionless pulley to a second block of mass m 2 80 kg hanging vertically M a What is the magnitude of the acceleration of each block m 0 74 m s m s m 0 74 b What is the direction of the acceleration of m O m accelerates downwards O not enough information m accelerates upwards X c What is the magnitude of the tension in the cord 18 29 XN raw a free body diagram for block 1 and another one for block 2 For block 1 write Newton s second law for motion along the inclined plane For block 2 write Newton s second law for motion along a vertical

19 Two blocks of equal mass of 4 kg are conne a string passing over a smooth pulley as shown in the figure The acceleration of the centre of mass of the system is g 10 m s T 4 kg Smooth 51 5 m s 3 107 10 m s 4 kg 2 y Lox 15 m s 2 4 21 21 m s

You have two strings that you can use to connect three masses as you see in the diagram m 2kg m 1kg m 5kg They are placed on a frictionless surface String A can only bear a tension of 10N and String B can only bear a tension of 20N How do you arrange the two strings s that you can apply the maximum force and achieve the maximum acceleration What are the maximum force and the maximum acceleration

it takes to reach the ground g 9 8 m s 178 4 m 59 13 m s 10 03 s An object is thrown straight up with a speed of 30 m s How high above the point of release is it and what is its velocity after 1 2s 2 6 s How high does it rise g 9 8 m s 19 4 m s 40 4 m 28 8 m s 3 6 m 45 9 m

na variant of the famous problem of static equilibrium of a ladder what minimum force F must be exerted on the foot of the ladder via a rope at angle to the vertical such that the normal force Ny of the floor on the ladder goes to zero Fwl 0 Nw mg F Nf

4 The rate of mass of the gas emitted from rear of a rocket is initially 20 kg s If the speed of the gas relative to the rocket is 800 m s and mass of rocket is 1000 kg then the initial acceleration of the rocket is Take g 10 m s NCERT Pg 110 1 4 m s 2 16 m s 3 6 m s 4 12 m s

14 In the following arrangement table and pulley are smooth Rope is ideal The monkey of mass m moves upward with respect to the rope with acceleration a Find acceleration of block 1 3 M m g a M m 2m g ao M m m 2 4 m g a M m m 2g a M m

A motorcycle is moving with a velocity of 6 Okm hr and it takes 8secs to stop after the brakes are applied C alculate the force exerted by the brakes on the motorcycle if it s mass along with the

In the figure below the coefficient of kinetic friction between the 6 kg object and the surface is 0 2 The force F in N necessary to pull both blocks to the right with an acceleration of 3 m s is Select one O a 88 O b 56 O c 72 O d 40 2 kg 6 kg

kg block B rests as shown on a bracket A of same mass Constant forces F 20 N and F2 8 N start to act at time t 0 when the distance of block B from pulley is 200 cm Time when block B reaches the pulley is Assume that friction is sent every where Pulley and string are light F A 200cm m B F

Figure shows a weight of 30 Kg suspended at one end of cord and a weight of 70 kg applied at other end of the cord passing over a pulley Neglecting weight of rope and pulley Find the acceleration of the system and tension in the cord g 10 ms 2 30 kg H T T 70 kg

A small bar A resting on a smooth horizontal plane is attached by threads to a point P and by means of a weightless pulley to a weight B possessing the same mass as the bar itself The bar is also attached to a point O by means of a light non deformed spring of length l 50 cm and stiffness k 5 mg l where m is the mass of the bar The thread PA having been burned the bar starts moving to the right Find its velocity at the moment when it is breaking off the plane

Figure shows two blocks A and B having mass 2 kg and 4 kg moving with a speed 4 m sec and 2 m sec respectively The maximum compression in the spring and final velocity of 2kg block are respectively 4m sec K 10 N m 2m s 00000000 1kg Question Type Single Correct Type 1 2 24 2kg m 45 3 m s 24 V25m 3 m s 24 3 45 4 3 m s Smooth

A 5 Kg slider moves along a smooth straight rod in a vertical plane Attached to it is a mass less spring k 100 N m unstretched length 2 m When the spring is in horizontal position the speed of the slider is given by v 4 m s When the spring becomes vertical it s speed v in m s is g 10 m s 3m

4 A particle which is constrained to move along the x axis is subjected to a force in the same direction which varies with the distance x of the particle from the origin as F x kx ax Here k and a are positive constants For x 0 find the functional form of the potential energy U x of the particle

A particle is thrown vertically up with velocity 10 m s from a point P which is 10 m above the ground Time after which particle reaches the ground g 10 m s 10 m s 10 m 0 3 1 s O 3 1 s 02 S 3 s

The upper end of the uniform chain of linear mass density u is lowered with a speed v as shown the figure Find the reaction force offered by the ground after the chain falls through a distance y

body is at rest or moving at a constant speed in a straight line it will remain at rest or keep moving in a straight line at constant speed unless it acted upon by an unbalanced force This statement is accordin o Newton law of motion first second third

Pin P is attached to BC and slides freely in the slot of OA B Determine the rate of change d0 dt in rad s of the angle at the instant when h 4 m B 60 and 0 30 knowing that BC moves at a constant speed v 5 m s h No A C

Wind is blowing in the east direction at speed of m s which causes the rain to fall at some angle wit the vertical With what velocity should a cyclis drive so that the rain appears vertical to him A 2 m s south B 2 m s east D 4 m s south C 4 m s west OA B Correct Not Marked By You

A particle moves from rest at A on the surface of a smooth circular cylinder of radius ras shown At B it leaves the cylinder The equation relating a and Bis a 3 sin a 2 sin c 3 sin 2 cos a 82 17 b 2 sin a 3 cos d 2 sin 3 cos a B

86 Units and Measurements 18 The frequency of vibrations f of a mass m suspended from a spring of spring constant K is given by a relation of type f cm K where c is a dimensionless constant The values of x and y are 1

In the given diagram with what force must the man pull the rope to hold the plank in position Weight of the man is 60 kg Neglect the weights of plank rope and pulley Question Type Single Correct Type 1 2 3 4 150 N 300 N 600 N 120 N

Find M in kg for which m will start sliding over m Table on which m and m are placed is smooth u is the friction coefficient between m and m Given m 2 kg m 1 kg u 0 5 g 10 m s m III

d 2 70 A 20 kg box rests on the flat floor of a truck The coefficients of friction between box and floor are 0 15 and 0 10 The truck stops at a stop sign and then starts to move with an acceleration of 2 m s2 If the box is 2 2 m from the rear of the truck when the truck starts how much time elapses before the box falls off the rear of the truck How far does the truck travel in this time

3 64 The basket in a front loading automatic clothes dryer rotates about a horizontal axis The basket rotates so that the force exerted by the basket on clothes located at the basket s edge is zero at the top of the path If the radius of the basket is 0 65 m how fast must the basket turn to accomplish this

A fighter plane is flying horizontally at an altitude 2000 m with speed 720 km h At a particular angle of sight with respect to horizontal when target is seen the pilot drops a bomb in order to attack the target This angle is tan 1 1 2 3 tan 1 1 4 2 tan 1 4 tan 2

A steel wire of negligible mass length 21 cross sectional area A and Young s modulus Y is held between two rigid walls A small body of mass m is suspended from its middle point O as shown The vertical descent of the middle point O of the wire is 1 3 1 3 A B C mg AY 4mg AY 4 1 3 D 2mg AY 6mg AY 1 3 TTTT N G

A particle of mass m is released on a smooth track in vertical plane which transforms into a circular arc of radius R The reaction force exerted at the bottom most position will be m A 4R O mg O 7mg 8mg O 9mg R

A rod is kept an angle of 60 with the horizontal by the help of a string in vertical plane The string is now cut at t 0 Find the force in N applied by upper half section of the rod AC on the lower half section of the rod BC just after t 0 Take mass of the rod 6 4 kg and g 10 m s Take 193 13 86 rod String B