Friction Questions and Answers

A 90kg 120Kg 50 B 40Kg What is of Mr Incredible s feet so he stays in equilibrium a Determine the acceleration of the system if is less than your answer from 1 and 0 6 b Determine T and T c Verify Mr Incredible s acceleration using T and T

63 A solid sphere of mass m and radius R is released the top of an inclined plane such that it rolls down without slipping If the coefficient of friction is u and the angle of inclination is with the horizontal then the force of friction acting on the body is 1 mgcos 2 mgsin mgsin 3 2mgsin 3

A cat dozes on a stationary merry go round at a radius of 5 8 m from the center of the ride The operator turns on the ride and brings it up to its proper turning rate of one complete rotation every 7 7 s What is the least coefficient of static friction between the cat and the merry go round that will allow the cat to stay in place without sliding

m 20 In the figure provided a crate of mass m sits at rest on a 20 ramp and is connected to another crate of mass 1 54 kg by a rope and pulley If the coefficient of friction is u 0 560 and 0 810 with the surface what acceleration will the mass mhave if it is slightly nudged and begins to be pulled up the ramp Assume the rope and pulley are massless 1 05 m s 2

Determine the minimum force P required to overcome static fra friction and to lift begin 100N block A as shown in figure The weight of 20 Wedge B is 5N and the co effecient of Static friction between all surfaces is 0 4 B A

Susan s 11 0 kg baby brother Paul sits on a mat Susan pulls the mat across the floor using a rope that s angled 30 above the floor The tension is a constant 29 0 N and the coefficient of friction is 200 Part A Use work and energy to find Paul s speed after being pulled 3 40 m Express your answer with the appropriate units VI HA

SolveLancer Test A front wheel drive car is moving in a hilly area Then which statement is incorrect The motion of wheels is pure rolling SolveLancer Test a If the car is accelerating up a slope then friction force on rear wheel is in backward direction b If the car is accelerating up a slope then friction force on front wheel is in backward direction c If the car moving up with constant velocity then friction force on front wheel is in forward direction d If the car is moving up with constant velocity the friction force on real wheel is zero

26 In the given figure F 200 N m 20 kg m 25 kg g 10 m s Find the friction acting on the block of mass m Take g 10 m s 25 kg 20 kg m m M 0 5 1 125 N Z T 2 28 100 F 200 N 0 5 2 120 5 N 4 1232 N f f 2002 f

5 A solid ball is fully immersed in a liquid contained in a cylinder The radius of cylinder is R A piston weightless is placed on the liquid surface If a pressure is applied on the liquid by a weight W placed on the piston then the fractional change in radius of ball is x Then the bulk modulus for the material of ball is given that x 1 2 1 W R X W 3 R x

Question No 15 Single Correct A A B C Fixed 37 777 For the given arrangement find force of friction on the block D 24 N 4 kg 12 8 N 4N 12 N 0 4 A

A football of radius R is kept on a hole of radius r r R made on a plank kept horizontally One end of the plank is now lifted so that it gets tilted making an angle 9 from the horizontal as shown in the figure below The maximum value of 0 so that the football does not start rolling down the plank satisfies figure is schematic and not drawn to scale A sino R Plank B tane 2r R 0 C sino T 2R D cose 2R

In the adjoining figure if the block starts of moving from rest work done by the frictional force from t 1 sto t 2s is A 60 J C 180 J B 120 J D 240 J 10 kg of a spring 37 0 5

A given object takes n times more time to slide down a 45 rough inclined plane than the time taken to slide down the similar but a smooth inclined plane The coefficient of kinetic friction between the object and the rough inclined plane is A B 1 C 1 1 n 1 1 2 n 5 2 0 D 1 n 1 1 n

In the below figure shown H 0 25 10 kg 15 kg ongaper smooth Find the maximum value of F below which blocks move together 1 235 3 F 425 N 2 135 165 4 N

A horizontal force of 49 N is just able to move a block of wood weighing 10 kg on a rough horizontal surface Calculate the coefficient of friction g 9 8 m s 1 0 5 3 0 75 2 0 25 4 0

A block of mass m is placed on a plank of mass M and given velocity V Friction between plank and ground is zero The coefficient of friction between the block and plank is and its value is such that block becomes stationary wit respect to plank before it reaches the other end Then m the work done by friction on the block is negative the work done by friction on the plank is positive the net work done by friction is negative net work done by the friction is zero Vo M

block of mass of 2 kg is at rest on rough surface Coefficient of friction between block surface is 0 4 A horizontal force F is applied on the block Variation of F is presented in figure Maximum speed in m s of block during the motion is vo then find value of Vo 5 FA 2kg 0 4 F 12N 4N t

For given figure ma is 30 kg mg mc 5 kg respectively All contact surfaces are smooth g 10 m s2 Select the correct statemen B A Acceleration of block A B and C arc 1 m s 4 m s and 5 m s2 respectively Contact force between B Ground is 350 N Tension in string is 30N Contact force between B and C is 20 N

Two blocks A and B are separated by some distance and tied by a string as shown in the figure The force of friction in both the blocks at t 2 sec is A 4 N 5 N C ON 10 N F 21 m 1 kg H41 0 6 B 2 N 5 N D 1 N 5 N m 2kg H 0 5 F 5N

Two blocks of mass 2kg 3kg respectively are placed on rough inclined having inclination angle 0 37 as shown in the diagram N is the normal reaction between the two blocks 37 2kg 3kg H If H H 0 5 a a 0 N 0 If H H 0 5 a a2 0 N 0 2

4 57 Figure 4 115 shows a boy on a horizontal platform A on a smooth horizontal surface holding a rope attached to a box B Boy pulls the rope with a constant force of 50 N The combined mass of platform A and boy is 250 kg and that of box B is 500 kg The velocity of A relative to the box B 5 s after the boy on A begins to pull the rope will be TA A 1 m s C 2 m s goodley AE Figure 4 115 B B 1 5 m s D 0 5 m s orig 30 A C 4 0 ba ORE he de ce th

fourth option without selecting any incorrect option second option in this case will result in 1 marks A ball lies on a carpet Carpet is kept on smooth horizontal floor Carpet is pulled as shown in figure There is no slipping between ball carpet ball Carpet pull Acceleration of center of mass of ball is in the direction of acceleration of carpet Acceleration of center of mass of ball is in opposite direction of acceleration of carpet O Direction of angular acceleration of ball is out of the plane of paper Work done by friction on ball carpet system is non zero

A truck is moving such that block of 1kg mass remain at rest w r t truck then Acceleration of truck is less than 5 m s Acceleration of truck must be greater than 20 m s If acceleration of truck is 25 m s2 then normal contact force between truck block is 25N If acceleration of truck is 20 m s2 then friction force between truck block is 10 N Truck 0 5 1kg

Two blocks A and B of masses 5 kg and 10 kg respectively are pushed on rough surface The contact force between the blocks is g 10 m s TTT 1 20 N 90 NA Rough B 0 4 2 40 N N IT

A block A of mass m is slipping down with constant speed on a rough wedge B of mass M kept at rest on a table as shown in figure Then B A Friction force on wedge due to table is zero B Friction force on wedge due to table towards left C Contact force on wedge due to table is greater than m M g D Contact force on wedge due to table is making non zero angle with vertical

Column I A The force exerted by X on Y has a magnitude Mg B The gravitational potential energy of X is continuously increasing C Mechanical energy of the system X Y is continuously decreasing D The torque of the weight of Y about point P is zero P X Y Column II p Block Y of mass M left on a fixed inclined plane X slides on it with a constant velocity q Two ring magnets Y and Z each of mass M are kept in frictionless vertical plastic stand so that they repel each other Y rests on the base X and Z hangs in air in equilibrium P is the topmost point of the stand on the common axis of the two rings The whole system is in a lift that is going up with a constant velocity r A pulley Y of mass mo is fixed to a table through a clamp X A block of mass M hangs from a string that goes over the pulley and is fixed at point P of the table The whole system is kept in a lift that is going down with a constant velocity s A sphere Y of mass M is put in a non viscous liquid X kept in a container at rest The sphere is released and it moves down in the liquid A sphere Y of mass M is falling with its terminal

In the figure shown is coefficient of friction between cylinder inclined surface Here e is continuously increased Find out required condition so that i sliding occurs earlier ii toppling occurs earlier 0 b

A wedge of mass m and a block of mass m are in equilibrium as shown Inclined surface of the wedge has an inclination a with the horizontal Each surface is frictionless The normal reaction on the wedge may be B m g sin a cos a D m g m g sin a cos a A m g cos a C m g m g cos a m1

In the figure shown a block of mass 10 kg is resting on the inclined plane of inclination 37 Two forces F and F parallel to incline plane are applied on the block in the directions shown If coefficient of friction is 0 5 a is acceleration of block and f the value of friction match the List I II 2 List I I I a 0 II a 1 m s III a 2 m s IV a 4 m s 37 A I S II T U III Q IV R C I Q S II P U III R IV T List II II P F 20 N F 10 N Q F 30 N F 10 N F 40 N F 40 N R S F 100 N F 70 N T F 80 N F 100 N U F 110 N F ON B I P II T U III R IV S D I S II Q U III R IV P

base length l and height h on an irregular surface as shown Then the minimum coefficient of friction between the chain and the surface must be equal to n h O Find n 0 25 0 5

D out of which ONLY ONE in correct A block of mass 1 kg is placed on the rough horizontal surface of a car moving with a constant acceleration a 2m s starting from rest as shown The net work done by frictional force on the block relative to ground in first 4 sec is A 8 Joule B 16 Joule C 32 Joule D 64 Joule 0 4 1 kg

A conveyor belt is moving at a constant speed of 2 m s1 A box is gently dropped on it The coefficient of friction between them is u 0 5 The distance that the box will move relative to belt before coming to rest on it taking g 10 ms is a 0 4 m b 1 2 m c 0 6 m d zero

A crate with a mass of 32 5 kg is pushed with a horizontal force of 150 N The crate moves at a constant speed across a level rough floor a distance of 7 05 m a What is the work done in J by the 150 N force 1057 5 J b What is the coefficient of kinetic friction between the crate and the floor

The coefficient of friction between the block of mass m1 3 00 kg and the surface in the figure below is uk 0 350 The system starts from rest What is the speed of the ball of mass m2 5 00 kg when it has fallen a distance h 1 75 m

Question 1 A block of mass 2 kg has an initial speed of 10 m s and moves on a surface whose coefficient of friction is uc 0 3 An external force of 12 N and oriented parallel to the inclined plane acts on the block What is the total work done by all forces on the block in 3 seconds F 2 kg 30

A solid cylinder is placed on a horizontal flat trolley When trolley start moving with an acceleration a in horizontal direction cylinder start rolling without sliding If F F are component of static friction acting on cylinder along the axis of cylinder and perpendicular to it Then from the diagram A F C F masin 0 3 1 ma cos 0 3 F F B Fy 2 a ma sin 0 3 D F ma cos

34 SS M ar A metal rod of length L and mass m is pivoted at one end A radius R L is attached at its center to the free end of the rod Consider two ways the disc is attached case A The disc is not free to rotate about its center and case B the disc is free to rotate about its center The rod disc system performs SHM in vertical plane after being released from the same displaced position Which of the following statement s is are true A Restoring torque in case A Restoring torque in case B B Restoring torque in case A Restoring torque in case B C Angular frequency for case A Angular frequency for case B D Angular frequency for case A Angular frequency for case B

Block A of mass 3 kg rests on another block B of mass 7 kg The coefficient of friction between A and B is 0 4 while the coefficient of friction between B and the horizontal floor on which B rests is 0 55 Find the force of friction between A and B when a horizontal force of 50 N is applied on the block B Use g 10 m s

In a linear centre line collision a particle with an initial speed vo strikes a stationary particle of the same mass If the final total kinetic energy is 25 greater than the original kinetic energy the magnitude of the relative velocity between the two particles after collision is O V O Va

10a A 1 0 kg copper rod rests on two horizontal rails 1 0 m apart and carries a current of 50 A from one rail to the other The coefficient of static friction between rod and rails is 0 60 What are the a magnitude and b angle relative to the vertical of the smallest magnetic field that puts the rod on the verge of sliding

Questions asked Prior to Medical Ent Exams 2005 19 A charged cloud system produces an electric field in the air near the earth s surface A particle of charge 2 10 C is acted on by a downward electrostatic force of 3 x 10 6 N when placed in this field The gravitational and electrostatic force respectively exerted on a proton placed in this field are 1 1 64 10 26 N 2 4 x 10 16 N 2 1 64 10 26 N 1 5 10 N 3 1 56 10 18 N 2 4 x 10 16 N 4 1 5 10 N 2 4 10 16 N

15 Three point charges q 2q and q are placed at points x 0 y a z 0 x 0 y 0 z 0 and x a y 0 z 0 respectively The magnitude and direction of the electric dipole moment vector of this charge assembly are AIPMT Prelims 2007 1 2 qa along x direction 2 2 qa along y direction 3 2 qa along the line joining points x 0 y 0 z 0 and x a y a z 0 4 qa along the line joining points x 0 y 0

48a Suppose you have a 135 kg wooden crate resting on a wood floor with coefficient of static friction 0 45 between these wood surfaces What maximum force can you exert horizontally on the crate without moving it N Submit Score 1 1 595 35 is correct 48b If you continue to exert this force once the crate starts to slip what will its acceleration then be The coefficient of sliding friction is known to be 0 25 for this situation

19 In the figure shown coefficient of friction between 8 kg block and surface is zero and coefficient of friction both static and kinetic between the blocks is 0 4 A force of 20 N is applied on 8 kg block as shown The acceleration of 4 kg mass is g 10 m s 0 4 1 4 m s 5 3 m s 4 kg 8 kg 0 20 N 2 0 5 m s 3 4 m s

A block of mass 5 kg is placed on a rough horizontal plane The coefficients of static and kinetic friction between the block and surface are 0 5 and 0 3 respectively A force of 100 N is applied at an angle 30 with the horizontal as shown in the figure The acceleration of the block will be g 10 m s 5 kg aroma 1 10 3 3 m s 2 20 m s 3 Zero 100 N 30 G

5 A block of mass 4 kg is placed on a rough horizontal plane A time dependent horizontal force F 2t N acts on the block The frictional force between the block and plane at time t 2 s is 0 2 4 N 2 8 N 3 10 N 4 12 N umg 9 F 26 1 fic 19 N I umg F FFS t Tox 0 21 4 102 12x 2

In the figure shown the mass of block A as well as that of B is same say m The system is held at rest by applying a force F as shown If the force is removed what is the acceleration of Block A in m s 0 2 0 F A 30 B

A uniform rod rests against a smooth vertical wall and a rough horizontal surface A horizontal force F is applied at the centre of mass of the rod such that the rod is in static equilibrium and the resultant of F and the weight of the rod intersect at the point P shown in the figure The angle in degree of friction for friction force between the rod and horizontal surface is 10x Find x value wall 30 30 P

M Answer the following by appropriately matching the list based on the information given in the paragraph A Block of mass m is placed on a fixed incline of inclination 0 and the coefficient of friction between the block and the incline is u List gives different possible values of 0 and list II gives different magnitudes of some quantity List List Il 30 37 III 45 IV 60 0 11 P 1 2 Q 3 5 R 1 12 m S 4 5 T 3 2 U 1

The horizontal force F acting on a block of 1 kg varies with time I in s as F N if coefficient of friction between the block and surface is 0 2 then the frictional force acting on the block at f 3s will be g 10 ms 2 A J 1 kg 220 2 1 3 N 2 1 N F 2 2N 4 O