Newton's law of motion Questions and Answers

earth A ball of mass 200 gm moving with velocity of 20 m s a player catches it If time taken to catch the ball is 0 5 sec then force applied on players hands will be 1 8N 2 4N 3 2N 4 ON A lift in m

A body is in equilibrium under the action of three forces on it For this it is necessary that the three forces 1 are in or should be in a straight line 2 should pass through the same point and do not lie in the same plane 3 should pass through the same point and lie in the same plane 4 should be mutually perpendicular to each other and pass through a common point Newton s third lau

Learning Task No 4 Try to solve this problem about balance and unbalanced forces using G R E S A method Write your answer in a separate sheet of paper 1 A boy and a girl are pulling a heavy crate at the same time with 7 units of force each What is the net force acts on the object Is the object unbalanced balanced or 7unit 10 7unit 2 What will be the net force of the object if a boy and a girl pull the heavy crate at the same time in opposite directions with 20 units and 10 units of force respectively the object move To what direction will it move Will 20 3 Suppose another girl pulls the heavy crate with 10 units of force in the same direction as the girl what will be the net force that will act on the object Will the object move 10

A Force F yi xi acts on a particle which moves on OABC as shown in the figure Work done by F to move the particle from Y 0 a O 0 0 O to A is zero O to B is a O to C is a OABCO is zero B a a A a 0 X

8 A 2 B 4 C 6 5 D 0 5 In the figure shown string is massless and inextensible Pulley and spring are massless When the string is cut ratio of acceleration of block 2 to acceleration of block 1 is utamu 1 2m 2

Momentum of an object is 30 kg ms 1 What will be its momentum if the velocity is th 1 of its orginal magnitude but mass remains the same reduced to Options 6 67 kg ms1 7 5 kg ms1 18 kg ms1 120 kg ms1

A Force F yi xj acts on a particle which moves on OABC as shown in the figure Work done by F to move the particle from Y O to A is zero OO to B is a DO to C is a OABCO is zero 0 a 0 0 B a a a 0

A force of 10 N is applied to a mass of 10gm for 10 seconds The change of momentum in kgm sec units will be 1 10 3 1000 2 100 4 0 01 A ball moving with a velocity 20 m sec has a mass of 50 am If collides against a wall normally and

50 A man of mass m has fallen into a ditch of width d Two of his friends are slowly pulling him out using a light rope and two fixed pulleys as shown in figure Both the friends exert force of equal magnitudes F When the man is at a depth h the value of Fis a mg d 4h b hmg 4h c dmg d mg 26 h d

17 Three forces F 21 41 N F 2j k N and F K 41 21 N are applied on an object of mass 1 kg at rest at origin The position of the object at t 2 s will be 1 2 m 6 m 2 4 m 8 m 3 3 m 6 m 4 2 m 3 m

Following forces start acting on a particle at rest at the origin of the co ordina system simultaneously F 41 5j 5k F 8 6k F 3 4 7k and F 21 33 2 then the particle will move a In x y plane c In x z plane b Iny z plane d Along x axis gul cor

All the surface is smooth and pulley are ideal then find mass m so that contact force between inclined and block of mass m becomes zero A C m M m tan0 1 M m tan0 1 0 M B D m m g M m m M m coto 1

When a ball is freely fallen from a given height it bounces to 80 of its original height What fraction of its mechanical energy is lost in each bounce 1 0 20 2 0 60 3 0 40 4 1

A mass is suspended by a rope from a rigid support at A as shown in figure Another rope is tied at the end B and it is pulled horizontally with a force F If the rope AB makes an angle with the vertical in equilibrium then the tension in the string AB is A F sin 0 C F cos 0 B M F B F sin 0 D F cos 0

A body of mass 2 kg is sliding with a constant velocity of 4 m s on a frictionless horizontal table The force required to keep the body moving with the same velocity is A 8 N B ON C 2 10 N D 12 N

A mass of 10 kg is suspended by a rope of length 2 8m from a ceiling A force of 98 N is applied at the midpoint of the rope as shown in figure The angle which the rope makes with the vertical in equilibrium is A 30 C 45 T 0 T 10kg 98N B 60 D 90

One end of a string 0 5 m long is fixed to a point A and the other end is fastened to a small object of weight 8 N The object is pulled aside by a horizontal force F until it is 0 3 m form the vertical through A 10 B T C F

the The string shown in figure is passing over smooth pulley rigidly attached to trolley A The speed of trolley is maintained constant and equal to VA The speed and magnitude of acceleration of block B at the instant shown in figure is assume that block does not oscillate 1 VB 1 34 5 x 3 cm VA 2 ag 0 3 VB VA h 4 cm

A wooden block of mass 1 kg is attached to the hook of a spring balance The spring balance is then raised with an acceleration of 9 8ms2 The apparent weight of the body is A 1kg wt 78 2 B 2kg wt C 3kg wt D 4kg wt in a rocket accelerating upward with an acceleration of

A uniform slender rod of mass m and length L is released from rest with its lower end touching a frictionless horizontal floor At the initial moment the rod is inclined at an angle 30 with the vertical Then the value of normal reaction from the floor released will be A 4mg 7 B 5mg 9 C 2mg 5 D None

A system is shown in figure All contact surfaces are smooth and string is tight inextensible Wedge A moves towards right with speed 10 m s velocity of B relative to A is in downward direction along the incline ha magnitude 5 m s Select correct option s regarding velocity of block C Horizontal component of velocity is 4 m s Horizontal component of velocity is 14 m s Vertical component of velocity is 8 m s Vertical component of velocity is 26 m s A B 37 C

A moving block of mass 2m collides with another stationary block having mass 3m The lighter block comes to rest after collision when initial velocity of the lighter block is v then value of coefficient of restitution e will be 113 112 2

The resultant of two forces acting at 150 is 10 kgwt and is perpendicular to one of the forces The magnitude of smaller force is f 1 10 3 kgwt 60 2 20 3 kgwt 3 20 kgwt 4 10 kgwt

Consider a large fish that swims towards and swallows a small fish at rest see fig If the large fish has a mass of 5 kg and swims at 1 m s towards the small fish having mass of 1 kg what is the velocity of the large fish immediately after the lunch Neglect the effects of water resistance

A charged oil drop of mass 10 g and charge 10 nC is suspended between two parallel horizontal charged plates The electric field between the plates is da de s s uuide ag ra G14 GIDI SI D 10 10 33 OPTIONS MARK FOR REVIEW CLEAR SELECTION OA 4N C OB 6 N C OC 10 N C OD 8 N C

Two blocks B B of masses m m respectively are connected with the help of a pulley and string as shown Upper surface of vehicle is smooth but vertical surface is rough Given a g 7 m 7 5 m Blocks B B do not slide then minimum coefficient of friction between block B and side of vehicle is B B

A force F 3a B 7aj Yk when applied on a particle of mass m 10 kg the particle accelerates with acceleration F 2 4 73 m s Force applied and acceleration of a particle bear the relation Image not present ma This equation is known as Newton s second law of motion Find numerical value of the expression a B 2y

The elevator E shown in the figure moves downward with a constant velocity of 15 ft s The relative velocity of the cable C with respect to the elevator is 1 30 ft sec M C E W min 2 45 ft sec

of mass m placed inside the wedge Block is free to move inside groove of the wedge Neglect friction between all the surfaces System is released from rest Mark the CORRECT option Block m Wedge M A Contact force between block and wedge is non zero

Two blocks of masses m and m being connected with a light spring of stiffness k are driven with forces F and F on a smooth horizontal plane If the blocks move with same acceleration a the value of a is 1 F F 2 m m 2 F Fm m F 2 m m 1 F 3 2 m m F a m oooooo m F

The 50 kg homogeneous smooth sphere rests on the 30 incline A and bears against the smooth vertical wall B Calculate the contact force at A 500 3 2 500 N 1000 3 4 1000 N 1 3 N N A 30 B

In the adjacent figure a uniform disc of mass 2m and radius 1 2 is lying at rest on a smooth horizontal surface A particle A of mass m is connected to a light string of length whose other end is attached to the circumference of the disc Initially string is just taut and tangential to the disc particle A is at rest In the same horizontal plane another particle B of same mass m moving with velocity Vo perpendicular to string collides elastically with A Just after impact which of the following statements will be true B 3 Vo l 2m A m

In the arrangement shown in figure the mass of rod is 1 5 time as great as that of the ball the length of the rod is 1 The masses of the pulleys and the threads as well as the friction are negligible The ball is set on the same level as the lower end of the rod and then released How soon will the ball be at opposite end of the rod www 1 70 g 6 D 70 2 4 70 2g 50

Ratio of kinetic energy in two systems of units is 4 and ratio of speed is 2 and ratio of acceleration is 3 Then ratio of force in two systems is

0 A 15 kg block is initially moving along a smooth horizontal surface with a speed of v 4 m s to the left It is acted by a force F which varies in the manner shown Determine the speed of the block at t 15 seconds H Given that F 40 cos 1 12 5 m s 3 20 m s 40 A 5 F N TU 10 A 15 20 t s 2 8 5 m s 4 9 5 m s

A board of mass m is placed on a frictionless fixed inclined plane that makes an angle 0 37 with the horizontal A block of same mass is placed on the board and is given quick push up the board with initial velocity v 8 m s The board does not move relative to the plane m 37 m Acceleration of centre of mass of system comprising of board and block is 12 m s Magnitude of acceleration of block is 24 m s The distance d covered by the block by the time its velocity drops to v 2 is 2 metre Magnitude of friction force between block and board is mgsin37

In the figure shown all surfaces are smooth and block A and wedge B have mass 10 kg and 20 kg respectively and the system is in equilibrium Find normal reaction between block A B spring force and normal reaction of ground on block B g 10 m s 37 B woooooo

3 Two blocks connected by a weightless string are slid ing down a plane Fig 2 44 of inclination 37 The respective masses of the blocks are m 4 kg and m 2 kg Coefficient of friction of the 1st block with the plane is 0 75 and that of the 2nd block is 0 25 Assuming that the string is taut find i the common accelera Fig 2 44 tion of both the blocks and ii tension in the string 370 Given in 270 m m

A bead slides on a fixed frictionless wire bent into a horizontal semicircle of radius R as shown in figure In addition to any normal forces exerted by the wire the bead is subjected to an external force that points directly away from origin and depends on distance r from the origin T according to the formula F Fo i then which of the following are correct Ro

A dynamometer D is connected with two bodies 13 of mass M 6 kg and m 4kg If two forces F 20 N F 10 N are applied on masses according to figure then reading of the dynamometer will be 000000 F 20N 1 10 N 3 6 N M m F 10N 2 20 N 4 14 N fast gel F 10Niger strifa t F 20N D M 6 kg a m 4kg F 20 N 1 10 N 3 6 N M 000000 m 2 20 N 4 14 N F 10N

A bob of a simple pendulum of mass m rests one the inclined plane of a wedge If the wedge moves with a velocity v and acceleration a disregarding friction at each surface A Tension in the string is mg sine B acceleration of the bob is g a sin 0 C tension in the string is greater than mg sine D normal reaction on the wedge due to the bob is m g cos 0 a sin 0

A boy and a man carry a uniform rod of length 18 L horizontally in such a way that the boy gets 1 4th of the load If the boy is at one end of the rod the distance of the man form other end is 1 L 3 3 2L 3 2 L 4 4 3L 4 14 as aid fo as didi di uf asm 85 kuud 3 1 L 3 3 21 3 e fet at gut fuit 31144 2 L 4 4 3L 4

On Three blocks of masse m m m 2m and m 3m connected by two strings are placed horizontal frictionless surface as shown in figure A horizontal force F is applied to mass m as sho a The common acceleration of the block is m b DOS m m F 3m m3 c F 5m F d F 6m di

Three particles A B and C each of mass mare lying at the corners of an equilateral triangle of side L If the particle A is released keeping the particles Band C fixed the magnitude of instantaneous acceleration of Ais L m AQ L

16 A ball falls vertically onto a floor with momentum p and then bounces repeatedly If the coefficient of restitution is e then the total momentum imparted by the ball on the floor till the ball comes to rest is P 1 p 1 e 2 e 3 p 1 2 4 p 1 e

Three blocks of masses m m2 and m3 are connected by massless strings as shown on a frictionless table They are pulled with a force T3 40 N If m 10 kg m 6 kg and m3 4 kg the tension T2 will be GCC m m T T 1 20 N 2 40 N 3 10 N M3 T3

In the arrangement shown in the fig the block of mass m 2 kg lies on the wedge of mass M 8 kg The initial acceleration of the wedge if the surfaces are smooth and pulley strings are massless is 30 3 m s then x is X my 60 MI 60

17 A ball collides with a fixed inclined plane of inclination 0 after falling through a distance h If it moves horizontally just after the impact the coefficient of restitution is 1 tan 0 2 tan 0 4 cot 0 3 cot 8 A machinist starts with three identical

Two Arctic explorers are pulling a supply sled with a total mass of 160 kg Alphonse pulls the sled with a force of 50 0 N E 25 N while Bela pulls the sled with a force of 80 0 N E 20 0 S Determine the acceleration of the sled 4

1 Four identical small blocks marked 1 2 3 and 4 with separations a b and c as shown in the figure are moving on a frictionless floor in a line all with a velocity v towards a wall If all the collisions are perfectly elastic with what velocities and separations will the blocks move after all possible collisions U U U 3 U