Friction Questions and Answers

15 A 40 kg box sits on a horizontal surface If the coefficient of friction between box and surface is 0 34 what horizontal force must be applied to give the box an acceleration of 2 00 m s 134 N 313 N 186 N 80 N 219 N

A 15 5 kg block is pushed to the right across a level surface at a constant velocity by a force P that is inclined 35 to the horizontal as shown The coefficient of kinetic friction between the block and the surface is 0 325 What is the magnitude of the force P P 35 15 5 kg

2 To keep a large crate moving across a rough floor you push down on it at an angle 8 27 as shown in the figure Find the force necessary to keep the crate moving at constant velocity given that the mass of the crate is m 36 0 kg and the coefficient of kinetic friction between the crate and the floor is 0 29 N

3 A 7 50 kg block is pressed against a vertical wall by a force F as shown in the figure below The coefficient of static friction between the block and the wall is 0 42 and the directional angle 8 for the force is 44 0 Determine the magnitude of the force F when the block is about to slide down the wall N

Q 118 A block of mass 2 kg is acted upon by a force Q 118 20 N when it is moving on a rough horizontal surface with speed 2 m s as shown in figure The magnitude of friction force acting on it is Take g 10 m s 2 m s2 kg 20 N 777777777777777777 0 5 1 Zero 3 20 N 2 10 N 4 30 N 2 kg CHIRIVICI E far 2 m s e R fa g 10 m s t 1 3 20 N 2 m s2 kg 20 N M 0 5 2 10 N 4 30 N

8 kg is connected to an empty bucket of mass 1 kg by a massless cord running over an ideal pulley The coefficients of static and kinetic friction between table top and block are 0 5 and 0 4 respectively Sand is gradually added to the bucket until the block just being to slide The mass of sand added is g 10 m s 8 kg A block of mass M A 5 kg C 7 kg B 6 kg D 10 kg

3 Find direction and magnitude of the friction force and acceleration of the block in each case 5 kg M 0 2 0 1 a F 10 Nt b F 20 Nt Also find net force from ground on block in each case 6 N c F 30 Nt

A man standing on horizontal smooth surface consider air is absent but gravity is present Choose the correct statement 1 He can jump in vertical direction 2 He can move in horizontal direction 3 He can fall in forward or backward direction 4 All of these

One or More than one correct type his section contains 06 multiple choice questions Each question has FOUR options A B C and D ONE OR MORE THAN ONE of these four options is are correct Consider a rope of mass 4m and length 4R on a fixed rough pulley of radius R as shown in the figure The rope is in equilibrium Length of vertical hanging parts is shown in the figure A B C D HR Torque of tension force about O on pulley is 4mgR Torque of normal force between rope and pulley on pulley about O is zero Torque of friction force between rope and pulley on pulley about O is mgR Torque of friction force between rope and pulley on pulley about O is zero 2 R

The system is released from rest in the position shown Calculate the tension T in the cord and the acceleration a of the 30 kg block The small pulley attached to the block has negligible mass and fric tion Suggestion First establish the kinematic rela tionship between the accelerations of the two bodies 4 3 Hs Hk 0 25 30 kg 15 kg K

4 101 A cannon of mass Mlocated at the base of an inclined plane shoots a shell of mass m in a horizontal direction with velocity v To what vertical height does the cannon ascend the inclined plane as a result of recoil if the angle of inclination of the plane is a and the coefficient of friction between the cannon and the plane is u Ans h 2 sina m vo 2 M sing 1 a

The coin is placed on stationary turn table in the position R 0 4 m and 0 0 The static coefficient of friction between coin and turn table is 0 2 If the turn table is started with the constant angular acceleration a 1 5 rad sec the angular velocity o when the coin starts slipping will be 21 19 C 19 rad sec D 21 rad sec 2 2 A rad sec B rad sec

Q 92 The work done by the frictional force Q 92 N 5 N 1 on a surface in drawing a complete circle of radius r 1 x metre on the surface by a pencil of negligible mass with a normal pressing force N 5 N p 0 5 is 1 0 J 3 2 J 2 3 J 4 5J farve as got get an aff 1 0 J 3 2 J 1 p 0 5 2 3 J 5J

100 m s on a parabolic shaped bridge AFOE Q 19 A car of mass m 1000 kg is moving with constant speed v of span 40 m and height h 20 m as shown in the figure Then the net force applied by the bridge on the car when the car is at point F is O A 5000 52 N B 5000 2 A N E 10m B C h l C D E 10000 2 N 2 D 5000 N V5

In an experiment to study the rolling of an object on an inclined surface a uniform solid sphere is released on a rough inclined surface of a given inclination 8 The acceleration of center a and force of friction facting on the sphere are measured for different values of u Which of the following graph correctly represents the data obtained A c azg d ch AA CI GEYYA ge7 fay yg ugu yg agxu du na na yz maa aa 92 93 Gla gat fay he ma e cura adu da fc 493 62 1 A4 ata i us su f a R A rl B f C D Correct Answer a Correct Answer a f

A block slides down an inclined plane of slope of angle 0 with a constant velocity v It is then projected up the plane with an initial velocity u What is the distance upto which it will rise before coming to rest

In a rough horizontal circular groove of radius r 10 m a particle of mass 1 kg is given a velocity vo along the tangent at same instant of time when angle travelled by radius is 0 velocity of particle is 10 m s Coefficient of friction 0 07 Calculate dE d0 at this moment where E is kinetic energy

56 veen block Q 10 Two blocks A and B are lying on the table as shown in the figure The coefficient of friction A and block B is The coefficient of friction between block B and ground is also An external force F applied in the direction shown the maximum value of the force F that can be applied without moving the block i A 2mA MB g B mA MB g A mB MA B O C 2mA m 2 g D 3MA m g

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other The source is moving with a speed of 19 4 ms 1 at an angle of 60 with the source observer line as shown in the figure The observer is at rest The apparent frequenc observed by the observer velocity of sound in a 330 ms is Re AIPMT 2015 ni S 1 97 Hz 3 103 Hz 60 S 2 100 Hz 3

3D 2 Two blocks of masses m and 2m are placed one over the other as shown in figure The coefficient of friction between m and 2m is u and between 2m and ground is H If a horizontal force Fis applied on upper block and 3 Tis tension developed in string then choose the incorrect alternative H a If F mg T 0 3 ta c If F 2 mg T umg 3 2m b If F mg T 0 d If F 3 mg T 0 3m 111

31 A chain of length L and mass M is IS on a table such that the part falling on the table comes to rest instantaneously The force acting on the table when x part of it has lied on the table is 2 3 2Mxg L Mxg L Mxg L pla

based on the information given in the paragraph A system of three masses m 2 kg m 3 kg and m3 5 kg are place on the smooth ground as shown in figure Friction coefficient between mass m and m is 0 2 and between mass m and m3 is 2 0 3 Smooth Assume that the masses do not fall off from each other in due course of motion List I gives the four entities regarding system of masses and List Il gives the magnitude of some quantity responses in respective SI units for the corresponding masses once they are subjected to given situation as stated below List l 1 For mass M P 8 II For mass m Q 2 III For mass m3 R 11 3 IV For m with respect to m3 S 2 3 T 3 U O m2 A ERAGI m 2 kg m 3 kg m3 fr FERIDA 0 2 I II GHI M 20 3 1 f THE M B m m m3 D I TER UR 3 A c FITT fach Half a chRUI GHA YC GAR G42 MR T5 1 M3 a fag IV m3 m a fag Achly te R410 34 a far m m m3 List II 5 kg RRETTI HA M P 8 Q 2 R 11 3 S 2 3 T 3 U O difed ur ufafeui a 4 yzf 11 11 Question If at t 0 masses m m and m3 are given a horizontal velocity in same direction as 1 m s u 6 m s and u3 10 m s respectively then correct match for the velocity of stated system of mass at t 1 sec will be M M 7 m c 4414 21 fa shHRT U 1 m s 4 6 m s 3 10 m s ft A fay 1 Acht T II P III U IV U T II P III P IV U I T II S III R IV U E Q II P III U IV P

A mass of 2 kg rests on a horizontal plan The plane is gradually inclined until at angle 30 with the horizontal the ma just begins to slide The coefficient of sta friction between the block and the surface NCERT I XI Pg 10 2 3 1 3 23 12

229 A block of mass 2 kg is allowed to slide from rest on a rough incline plane of coefficient of friction 0 5 Angle of inclination is 30 The contact force acting between the block and the plane is 1 5 10 N 2 5 15 N 3 10 3 N 4 10 5 N

4 All of these 70 The friction force acting between 10 kg block surface is Take g 10 m s yolluq etm 0 1 1 60 N 20 kg 10 kg 0 2 at brucip ert aevsel px SMOS 1 2 5 N 5 N els janit bruong erit zevsel p 80E S bruong ent zevsel pxl SMA 8 100 3 20 N 4 30 Nuit bruop en zeysel na

84 The upper half of an inclined plane of inclination 10 is frictionless while lower half is rough A body start to slip from top of inclined surface and come mu to rest at bottom The coefficient of friction u at lower half of plane is 1 2 cote 2 cote 3 tang tack

In a collision experiment you have pendulum with bob of mass 4 kg and length 1 m initially held at an angle 600 with the vertical The bob of the pendulum hits a block of mass 5 kg initially at rest at its lowest position The block comes to rest after moving a distance 0 8 Find the coefficient of friction between block and table coefficient of and restitution 1m 5kg 4kg

A uniform rod of length 21 and mass mis suspended from one end by inextensible string and other end lies on smooth ground The angle made by rod with vertical is sin 1 If N and N represents the contact force from ground on rod just before and just after cutting the string then find the ratio of N 10 21 GWHA YG G454 93 yg At ach 3 Tau Au fh unda 42 Ma 21 g fuz 4 sin 1 1 31 Pa ct 27 Ac 4g au t a unaa fruch an s uaffa g ma Af GRA N N String 3 20

A small block of mass m 1 kg is at rest placed on a rough xy horizontal plane At t 0 a new force F t is applied that has components FX t 1N 1 N m y and Fy t 1 N s t coefficient of static friction and kinetic friction between block and surface is 0 4 At t 0 block in at origin then at what value of t block is on the verge of slipping A t 4 s B t 3 8 s C t 2 5 s D none of these 55

constant acceleration a on a rough plane If the coefficient of friction between block and ground is u the power delivered by external agent after time t from beginning is equal to A B C ma t mgat m a mg t

50 An iron chain lies on a rough horizontal table It starts sliding when one fourth of its length hangs over the edge of the table The coefficient of static friction between the chain and the surface of the table is A 1 2 B 1 3 C 0 D 1 4

The force acting on the block pushing of the block will be possible along the surface if fagur v af 1 tane Fac F mg 0 m 2 cote 0

m A box of mass 8 kg is placed on a rough inclined plane of inclination 0 Its downward motion can b prevented by applying an upward pull F and it can be made to slide upwards by applying a force 2F Th coefficient of friction between the box and the inclined plane is 1 tan 0 2 3 tan 0 3 tan 0

Figure 5 84 shows a cart of mass Mon which another mass m is placed and attached to a pole on cart by a spring of force constant k If the friction between m and surface of cart as well as between cart and floor is neglected find the time period of small oscillation of cart block system 6rrrrrrrrrr ma m M

4 1200 N A 40 kg slab rests on a frictionless floor as shown in the figure A 10 kg block rests on the top of the slab The static coefficient of friction between the block and the slab is 0 60 while the kinetic friction is 0 40 The 10 kg block is acted upon by a horizontal force 100 N If g 9 8 m s the resulting acceleration of the slab will be 100N 10kg 40kg 1 0 98 m s 2 1 47 m s 3 1 52 m s

A ho 1 2 kg against a vertical wall The coefficient of static friction between the wall and the block is 0 5 and the coefficient of kinetic friction is 0 35 Assuming that the block is not moving initially Which one of the following choices is correct 12 N 1 2 kg en ont un afer dar faes va alar da fa di 0 5 0 35 6 g far faz 13 facc 12 N kg Take g 10 m s 1 Block moves vertically downwards 2 Block moves vertically upwards 3 Block will not move and force exerted on the block by the wall is 12 N 4 Block will not move and force exerted on the

Q14 For rolling condition predict Disc rough horizontal surface F a Kinetic friction is in right direction on floor b There is no friction c Static friction will be in right direction on floor Correct Answer 4 d Static friction will be in left direction on floor

1 A block of mass m is initially stationary relative to the plank of mass M If us between ground and M the maximum value of F for no relative sliding between M and m is A mg B Mg m M F m and no friction exist C mg 1 D None of these 3

An 80 kg baseball player slides to a stop at third base The coefficient of kinetic friction between the player and the ground is 0 70 His speed at the start of the slide is 8 23 m s a Calculate his acceleration during the slide b How long in time does he slide until he stops

For the system shown in figure both the block A and B are moving together If coefficient of friction between both the blocks is u the work done by to as the friction on block B is 1 Zero 3 Positiva B A smooth F 2 Negative A DI

Find the tension in the string in situation as shown in the figure below Forces 120 N and 100 N start act when the system is at rest 120 N 10 femax 90 N smax f 20 60 N 100N

Find the accelerations of blocks A and B for the following cases a 9 5 m s A 0 and 0 1 B 0 and 0 1 C 0 1 and R H P a B A Q a 9 m s a 10 m s M 1 0 R a a g 10 m s 1 0 14 1 0 and u 0 1 1 kg A 1 1kg B 10 N S a 1 a 9 m s 0 1

Following figure shows a logic gate circuit with two inputs A and B and output X The voltage waveforms of A B and X are as given A HHH A Logic B circuit The logic gate is AND NAND X O OR B t t t3 to 15

5 Assume that a drop of liquid evaporates by decrease in its surface energy so that its temperature remains unchanged What should be the minimum radius of the drop for this to be possible The surface tension is T density of liquid is p and L is its latent heat of vaporization 2 T pL 2013 4 pL T 1 T pL 3 2T pL japonded with its

6 Infinite number of bodies each of mass 2 kg are situated on x axis at distance 1m 2 m 4 m 8 m respectively from the origin The resulting gravitational potential due to this system at the origin will be NEET 2013 a G b 8 3 G c 4 3 G d 4 G dies

In the shown figure what amount of force and in which direction we should apply so that net force acts along axis only O SN 2N A 3N along ve of y axis B 3N along ve of y axis C 2N along ve of x axis D 2N along ve of x axis

Man is running on the horizontal road without slipping If man is increasing his speed at the rate a m s Choose correct option Work done by friction is ma t2 in t sec Work done by friction is zero Work done by Normal is zero Work done by gravity is zero

Two bodies A and B are thrown upwards simultaneously with same speed Mass of A is more than hat of B If same constant resistive force is applied on both bodies by air then 1 Both bodies will reach up to same height 2 A will reach up to more height than B 3 B will reach upto more height than A 4 Any one of above three may be possible it depends on initial cpood of both hoding

b Consider two scenarios A ball of weight 10 N rolls on the floor and a block of weight 10 N slides on a table In which case will the applied force required to just set the body in motion greater Why 2 2 4 marks A pin jointed truss is loaded and supported as shown in figure i Identify the members

19 A block mass Mkg is placed on a rough inclined plane A force Fis applied parallel to the inclined as shown in figure such that it just starts moving upward The value of Fis H 1 Mg sin 9 uMg cos 0 2 Mg sin 0 uMg cos 0 3 Mg sin 0 4 Mg cos 0 20 Figure shows two block system 4 kg block rests on