Friction Questions and Answers

A block of mass 6 kg is lying on a rough horizontal surface The angles of limiting and kinetic frictions are 53 and 37 respectively A horizontal force enough to set the block into motion is applied If we continue to apply the force by how much must the force be reduced to move the block with uniform velocity on the surface g 10 ms 2 and tan370 3 4 A 20 N B 45 N C 80 N D 35 N

A smooth plane of certain length is held at an angle 300 with the horizontal A rough plane of same length is held at an angle 45 A body released at the top takes the same time to arrive at the bottom on both the planes The coefficient of friction between the body and the rough plane is nearly

In the shown figure all surfaces are rough Block B is attached with a load of mass 6m through an ideal string passing over an ideal pulley Coefficient of friction is 0 2 between all the surfaces The correct option is friction force on C due to B is mg friction force on A is zero A B C D acceleration of block B is Load remains at rest 55 A 3m B 2m C m D 6m

30 A light block P on a horizontal tabletop placed equidistant from the pulleys supports a load with the help of a cord as shown in the figure If the minimum and the maximum forces applied by hand to keep the system in equilibrium are Fmin 40 N and Fmax 90 N calculate mass m of the load Acceleration due to gravity g 10 m s P

Two blocks A and B of masses m and 2m are initially at rest Length of block B is L and block A is placed at the right end comer c block and the friction coefficient between them is u 1 2 At 1 0 a constant force 5mg F ma 2 begins to act on block B towards right Just when the block A leaves B wind begins to blow along y direction which exerts a constant force 2 on A Assume the size of block A is small compared to B and neglect any rotational effects and toppling of block B Given h 1 2 m L 1m and g 10 m s J O L 29g 4 2m mA wind The magnitude of relative acceleration of A with respect to B in m s2 just after the block A leaves A leaves B is Assume wind does not effects motion of B O 10g BF wwwmX Smooth

At a construction site an iron rod of mass 2 kg and length 1m is kept resting on a vertical wall and horizontal floor as shown in the image Find out the minimum coefficient of friction between ground and rod so that it can be inclined at an angle of 45 degree without slipping

A 2 kg block is gently pushed from rest at A and it slides down along the fixed smooth circular surface If the attached spring has a force constant k 20 N m What is unstretched length in m of spring so that it does not allow the block to leave the surface until angle with the vertical is 8 60 A R 2 m Answer reelle B

N 8 ND 22 A force of 20 N along the line of the greatest slope is required to slide a block upwards with constant speed and a force of 8 N along the line of the greatest slope is required to slide the block downwards with constant speed on an inclined plane The force of kinetic friction between the block and the plane is

ons 42 to 44 are based on the following physical situation A horizontal conveyor belt is running at a constant speed u 3 0 m s A small disc enters the belt moving horizontally with a velocity 4 0 m s that is perpendicular to the velocity of the belt Coefficient of friction between the disc and the belt is 0 50 2 What can you predict regarding the path of the disc a It is a parabola relative the belt b It is a straight line relative to the belt c It is a parabola relative to the ground d It is a straight line relativo to the ground 43 What should the minimum width of the belt be so that the disc always remains on the belt a 0 9 m c 2 0 m b 1 6 m d 2 5 m 4 What is the minimum speed of the disc relative to the ground b 1 8 m s d 3 0 m s a 0 0 m s c 2 4 m s 17

Starting from rest a body slides down a 37 in clined plane in thrice the time it takes to slide down the same distance in the absence of friction The coefficient of friction between the body and the inclined plane is 1 0 33 3 0 25 2 0 67 4 0 80

A block of mass m is placed over a plank of m M M m which rests on a smooth inclined plane as shown in figure If the coefficient of friction between the plank and the block is u and the system is released from rest then the frictional force applied by the plank on the block M 0 1 Is up the inclined plane 2 Is down the inclined plane 3 Is zero

1 The coefficient of friction between a plane inclined at 60 and a body of mass 100 g kept on that plane is What minimum force should be applied along the 1 132 N plane so that the body can move upwards

Q 6 The coefficient of static friction between a car s tires and a level road is 0 80 If the car is to be stopped in a maximum time of 3 0 s its speed cannot exceed 1 2 4 m s 3 2 6 m s 2 7 8 m s 4 23 5 m s

27 A small block is kept on an inclined plane of adjustable inclination Coefficients of static and kinetic frictions between the block and the plane are and respectively The angle of inclination of the plane is gradually increased from zero until the block starts sliding How much speed will the block acquire in sliding down a distance 1 Acceleration due to gravity is g

MT 2010 A block of mass m is in contact with the cart C as shown in the figure The coefficient of static friction between the block and the cart is u The acceleration a of the cart that will prevent the block from falling statisfies 1 a g C a O PM m 2 a mg

Two blocks of masses mi and my connected by a spring of spring constant k are kept on a plank which in turn is kept over a frictionless horizontal surface as shown Coefficients of friction between masses m and m2 and plank are and 2 Plank is given a horizontal acceleration of magnitude a Then k M m M a elongation may take place in spring if b compression may take place in spring c elongation may take place in spring d there will be no elongation or compression in the spring if th

05 A solid cylinder of mass 12 kg and radius 5 cm is rolling without slipping down an inclined plane of inclination 30 with horizontal If coefficient of friction between the plane and cylinder is 0 8 then find the force of friction on the cylinder 1 20 N 2 48 3 N 4 10 N 3 60 N 16 Gravitational potential energy of a body on the surface

The spool of wire having a weight of 300 lb rests on the ground at B and against the wall at A Determine the force P required to begin pulling the wire horizontally off the spool The coefficient of static friction between the spool and its points of contact is s 0 25

Each of resistor shown in figure has resistance R Find the equivalent resistance between terminals JA and B Also find the ratio of maximum and minimum powers dissipated in any one of them A R www v R R www B

7 Two blocks A and B are connected to each other by a string and a spring of force constant k as shown in Fig The string passes over a frictionless pulley as shown The block B slides over the horizontal top surface of a stationary block C and the block A slides along the vertical side of C both with the same uniform speed The coefficient of friction between the surfaces of the blocks is If the mass of block A is m what is the mass of block B Em m C B 2 m

A body is placed on an inclined place and has to be pushed down in order to make it move The angle made by the normal reaction with the vertical will be Equal to angle of repose 2 Equal to the angle of friction 3 Less than the angle of repose 4 More than the angle of friction

Column I Normal reaction Force of friction under motion Acceleration of block Limiting friction 45 20 2N 4 kg 0 8 0 6 Column II a 12 SI unit b 20 SI unit c 16 SI unit d 2 SI unit b 388 14 a 15 a b 16 a 17 a b d

A car is negotiating a curved road of radius R The road is banked at an angle 0 The coefficient of friction between the tyres of the car and the road is us The minimum safe velocity on this road is 1 2 3 GR2 V 4 gR gR gR tan 0 Us 1 tan 0 tan 0 Us 1 tan 0 tan 0 Us 1 s tan 0 tan 0 Us 1 s tan 0

A solid cylinder is rolling without slipping on a having inclination 0 and the coefficient of static friction and kinetic friction The most appropiate relationship 1 tan 0 2 g 3 tan 0 2 MK 2 tan 0 3 Ms 4 tan 0 3 k

4 140 kN Consider the following statements a Frictional force between block and contact surface depends on area of contact b Frictional force may also act when there is no relative motion between the contact surfaces 6 3 4 12 13 A forc figure body i

0 A block of mass m lying on a rough horizontal plane is acted upon by a horizontal force P and another force Q inclined at an angle 0 to the vertical The block will remain in equilibrium if the coefficient of friction between it and the surface is 1 2 3 P P Qsin 0 mg Q cos 0 Pcos 0 Q mg Qsin 0 P Q cos 0 mg Qsin 0 P Osin A 10 Q

Why is the 3rd option incorrect pls explain Which of the following statement s is are incorrect x Rolling friction is greater than sliding friction Friction force opposes the relative motion Value of limiting friction is given by H Both 1 3

Question 5 A block of mass of 2 kg slides on an inclined plane that makes an angle of 7 6 with horizontal The coefficient of friction between the block and the surface is 3 2 1 What force should applied to the block so that it moves down without any acceleration 2 What force should be applied the block so that it moves up without any acceleration a 1 4 9 N 2 24 5 N b 1 4 9 N m s 2 4 9 N c 1 3 2 N 2 3 N d 1 5 N 2 25 N

Two blocks of masses m and M are joined with an ideal spring of spring constant k and kept on a rough surface as shown The spring is initially unstretched and the coefficient of friction between the blocks and the horizontal surface is l What should be the maximum speed of the block of mass M such that the smaller block does not move mmmmmmmmmm O O m ug Mm M m k M m k Mm O g V 2M m k KM None of these M

33 3 0 4N Smooth 2 kg 4 kg F 24 N In the arrangement coefficient of frictio between the two blocks is u 113 The force c 2 friction acting between the two blocks is 1 8 N 2 6 N 4 12 N 3 10 N 4 zero

A cylinder executes pure rolling without slipping with a constant velocity on a plank whose upper surface is rough enough to prevent slipping but lower surface is smooth The plank is kept at rest on a smooth horizontal surface The direction of motion of plank on smooth horizontal surface is ATTI 1 Towards A 2 Towards B 3 Depends on the ratio of masses of cylinder and plank smooth B

All surfaces are smooth string is light and pulley is frictionless Mark the correct statement s 15 N Options Acceleration of block A is 1 m s XAcceleration of block A and B will be same Acceleration of block C is zero Tension in string between pulley and wall is 10 N Solution Answer A C D 5 10 15 T 10a T 5a a 1m s

In the arrangement shown in the figure both the blocks are at rest initially and force Fis applied at t 0 then fa zeny zgda dat geh mr faghazu da fa fu la 7 ad A Smooth F B 10 kg C 5 kg 0 4 l 4 m H F 50 N Acceleration of A w r t B is 1 m s B HT g A I ca UT 1 m s B Acceleration of A w r t B is zero B Hug A i ca UI Q Correct Answer Time taken by A to fall from Bis 2 s BARA u fam m 944 2 D A does not fall from B A BRAZ

The equation of an SHM of amplitude a anc angular frequency w in which all the distances are measured from one mean position and time is taken to be zero at other extreme position is 2 x a cos w t 4 x a a cos w t 1 x a sin w t 3 x a a sin w t

A block of mass 10 kg is kept on a rough horizontal surface on which a force F is acting as shown in the figure The coefficient of friction between the block and the surface is 0 4 and the block is at rest The frictional force acting on the block is F C F 2 3 10 kg 0 4 3F 2 BE 30

32 The co efficient of static kinetic frictions are 0 6 0 3 The minimum force required to start the motion is applied and if it is continued the distance travelled by the body in 4 sec is g 10ms

40 An insect crawis up a CAT STAGE 15 slowly see fig The coefficient of friction between the insect and the surface is 1 3 If the line joining the center of the hemispherical surface to the insect makes an angle o with the vertical the maximum possible value of o is given by A ns coto 3 ns S Wh2m

38 A block of mass m slips on a rough horizontal table under the action of a horizontal force applied to it The coefficient of friction between the block and the table is The table does not move on the floor Find the total frictional force applied by the floor on the legs of the table Do you need the friction coefficient between the table and the floor or the mass of the table

33 A block of weight 200N is pulled along a rough horizontal surface at constant speed by a force 100N acting at an angle 30 above the horizontal The coefficient of friction between the block and the surface is

6 Figure shows two blocks in contact sliding down an inclined surface of inclination 300 The friction coefficient between the block of mass 2 0 kg and the incline is 4 and that between the block of mass 4 0 kg and the incline is Calculate the acceleration of the 2 0 kg block if a p 0 20 and 0 30 b 0 30 and 0 20 4 0 20 Take g m s 2 kg 4 kg 30 Ans 2 7 m s 2 4m s

1 You are riding in an automobile of mass 3000 kg Assuming that you are examining the oscillation characteristics of its suspension system The suspension sags 15 cm when the entire automobile is placed on it Also the amplitude of oscillation decreases by 50 during one complete oscillation Estimate the values of a the spring constant kand b the damping constant b for the spring and shock absorber system of one wheel assuming that each wheel supports 750 kg

34 An object takes 1 second to slide down a rough 45 inclined plane The time taken to slide down a smooth 30 inclined plane having the same slope length is 0 5 Ans 2 1 4 s

39 A block of mass 2 kg is pushed against a rough vertical wall with a force of 40 N coefficient of static friction being 0 5 Another horizontal force of 15 N is applied on the block in a direction parallel to the wall Will the block move If yes in which direction If no find the frictional force exerted by the wall on the block Ans It will move at an angle of 530 with the 15 N force

3 An aeroplane requires a speed of 72 kmph for a take off with 150m run on the ground The mass of the plane is 1500kg and the coefficient of friction between the aeroplane and the ground is 0 4 Assuming that the aeroplane accelerates uniformly during take off find the minimum force exerted by the engine of the aeroplane for take off

In the arrangement shown system consisting of a wedge and block A is slipping down the incline The direction of pseudo force acting on A in frame of wedge is A Fixed Upwards Downwards Along the incline upwards

2 2 4 6 10 12 14 16 t s 8 Fig 5 17 Figure 5 18 shows a man standing stationary with respect to a horizontal conveyor belt that is accelerating with 1 m s2 What is the net force on the man If the coefficient of static friction between the man s shoes and the belt is 0 2 up to what acceleration of the belt can the man continue to be stationary relative to the belt Mass of the man 65 kg

In the figure shown a ring of mass M and a block of mass m are in equilibrium The string is light and pulley P does not offer any friction and coefficient of friction between pole and M is The frictional force offered by the pole on M is uestion Type Single Correct Type 1 M 2 Mg directed up mg directed up m P

A block of mass 2kg is placed on the floor The coefficient of static friction is 0 4 Horizontal force of 2 8N is applied on the block The force of friction between the block and the floor is uestion Type Single Correct Type 1 2 3 2 8 N 8 N 2 0 N

All surfaces are assumed to be frictionless Calculate the horizontal force F that must be applied so that m and m2 do not move relative to m3 is 1 2 F 3 uestion Type Single Correct Type m g m m m m O m2g m1 m m3 m m g m2 m3 m m3 m g OO 3 m

2 The coefficient of friction between a plane inclined at 60 and that plane is plane is What mini a body of mass 100 g kept on that mum force should be applied along the plane so that the body can move upwards 1 132 N