Basic Physics Questions and Answers

45 Calculate the tangential stress on surface BB v force F acts on a solid cylinder fixed on one whose cross sectional area is as shown in figure 1 Fixed end F A B 0 B 2 F cross sectional area A 2A Sin20

3 2 Mo A and B are two concentric circular conductors of centre O and carrying currents I and I as shown in the adjacent figure If ratio of their radii is 12 and ratio of the flux densities at O due to A and Bis 1 3 then the value of 1 1 is 1 2 6 1 A B 2 4 12 1 4

cylinder surmounted by a cone The height of the cylindrical portion is 10m while the vertex of the cone is 15m above the ground The diameter of the cylinder is 18m The curved surface area of the cylindrical portion is A 200m B 150m c 180m 2

8 A rectangular coil of 100 turns and size 0 1 mx 0 05 m is placed perpendicular to a magnetic field of 0 1 T If the field drops to 0 05 T in 0 05 s the magnitude of the emf induced in the coil is Karnataka CET 2013 a 2 b 3 c 0 6 d 6

2 3 d 0 0 40 A toy car rolls down the inclined plane as shown in the fig IMP D L It goes around the loop at the bottom H What is the relation between H and h a H h c H h 2 b 4 H h Vay 3 H h 41 The mass of the bob of a simple 5 h T1 10

Vok 33 A uniform conducting rod of length is rotating with uniform angular velocity about point P in uniform magnetic field B as shown Calculate Vp Vo 1 82 B 3 28 P

A conducting medium is shaped in form of quarter of an annulus of radii b and a b 2a and thickness h as shown in figure The conductivity of medium is o If switch S is closed and switch S is open a current I is supplied by the battery if switch S is closed and switch S is open a current I is supplied by the battery If 12 2 10 find the value of n 1 Given n 2 0 5 and 7 10 S

A sphere is taken to the bottom of sea 3 km d then the fractional change in radius of spher Bulk modulus of the sphere is 9 8 108 N m 1 0 1 125 2 0 01 4 3 3 0 03

Online Mock Test Series for NEET 2020 35 A force F 25 N acts tangentially at the highest point of a sphere of mass m 3kg kept on a rough horizontal plane If the sphere rolls without slipping the acceleration of the centre of the sphere will be in m s 1 11 9 3 2 4 m 3 kg 2 8 6 4 7 9 F 25 N 4

52 A lift is coming from 8th floor and is just about reach 4th floor Taking ground floor as origina positive direction upwards for all quantities whi NCERT Exem one of the following is correct ax 0 v 0 a 0 b x 0 v 0 a 0 c x 0 v 0 a 0 d x 0 v 0 a 0 K instantaneous Speed

In a water treatment settling unit the average diameter of solid particles is 0 05 mm specific gravity of solids 1 2 and kinematic viscosity of water 1 01 centistokes According to Stoke s law the settling velocity is 0 54 mm s 2 7 mm s 0 27 mm s 54mmle a b c

A rectangular coil of 50 turns is hung vertically in uniform horizontal magnetic field of magnitude 10 2 T so that plane of the coil is parallel to field height of coil is 5 cm and width is 2 cm What strength of current must pass through it in order to deflect it through 30 if torsional constant of suspension wire is 10 9 N m per degree 32 A O 36 A O 69 A

A man is standing on a plank of length 2m and mass 150 kg which is placed on a horizontal frictionless floor If the man walked from end A tc B then actual i e with respect to ground displacement of the man is 1 2 m 7 A 50 kg 2 m 150 kg A1 0 2 1 5 m 4 1 m B

A 0 1 kg ball makes an elastic head on collision with a ball of unknown mass which is initially at rest If the 0 1 kg ball rebounds with one third of its original speed what is the mass of other ball

A star that has a mass equal to the mass of our Sun is located 7 50 x 10 km from another star that has a mass that is one ha of the Sun s mass The net gravitational force of the two stars on a space probe positioned between them is zero The probe s mass is 1 00 10 kg Determine the distance d of the space probe from the more massive star d 3 11 10 k

2 n small mercury drops of same size are charged to V volts each If they coalesce to form a single drop then its potential will be 1 n

2 There is a bicycle on a bicycle stand We know that its rear wheel s moment of inertia around its axis is 1 0 5 kg m and its radius is r 30 cm We speed up the wheel by repeatedly hitting it with a hand tangentially on its circumference in the direction of its rotation The speed of each hit in the rest reference frame is v 5 m s the mass of the hand is m 1 5kg the hand loses all its velocity in the reference frame of the point of impact after the impact the hand is moving around an elbow but we neglect rotation of the forearm If velocity of a point on the perimeter of the wheel after 10 hits be v value of a 23 y a 9 then

6 The two ends of a uniform conductor are joined to a cell of emf e and some internal resistance Starting from the midpoint P of the conductor we move in the direction of the current and return to P The potential V at every point on the path is plotted against the distance covered x Which of the following best represents the resulting curve 1 V E X 4 2 V KE

The expression for the capacity of a cape formed by compound dielectric placed betw plates of a parallel plate capacitor as shown figure is Area of each plate is A 1 EK EO d O A d d d3 K K K K3 X X X X X K X X X d d3 II k 2 KO Eo A d d d3 K K K3 V

3 2m 17 Linear momentum of a particle as function of time t is given by P Asin Bti Acos Ct A B C are constant Force acting on the particle is perpendicular to the momentum vector at any time t for 1 A B 3 A C 2 B C 4 C AB

A current is uniformly distributed over the cross section of a solid cylindrical long conductor of radius R The variation of magnetic field with distance from axis conductor is best represented by which graph y axis O B4 JF R View in Eng R

al e 11 If angle between two vectors A and B is 8 90 then value of A for which the resultant of the two vectors is perpendicular to A is 1 B cose 3 B sine 2 B sine B 4 cos0 ations

2 10 6 V m 4 2 10 4 V m 14 An earth s satellite is revolving in circular orbit in equatorial plane It is used for communication purpose The satellite can transmit signals upto 60 latitude on earth The angular velocity of satellite is 1 1 2 x 10 5 V m 3 10 V m GM 2R GM 15 A battery of emf 40V and internal resistance 202 is connected to a bulb of resistor 1892 What is the efficiency of the battery E 40 V 20 H for 1 A B 3GM 4R R 180 3GM BR dr 1 x dt 2 x0 1 10 3 7 5 16 A satellite is revolving round the earth in circular orbit with speed v An object of mass m is ejected from the satellite such that the object just escapes from earth s gravitational field At the time of ejection kinetic energy of the object was 1 mv 2 m 2 45 4 90 3 2m 4 mv 17 Linear momentum of a particle as function of time f is given by P Asin Bti Acos Ct A B C are constant Force acting on the particle is perpendicular to the momentum vector at any time t 2 B C 4 C AB 3 A C 18 A particle with position vector is moving in a circle about origin with angular velocity angular acceleration at which of the following relations is correct 19 Medical le 3 Change in angular momentum Angular impulse 4 Both 1 and 2 are correct In the given arrangement the charge on the 3 F capacitor is 23 24 2 F 1 10 C 2 20 C 3 30 C 4 25 C 20 A particle is moving with velocity equal to 0 4 m s is subjected to a constant acceleration of 0 15 m s for 2s in a direction perpendicular to initial direction of motion The magnitude of final resultant velocity is 1 0 3 m s 3 0 5 m s 10V 1 3P V TS 0 2 PV TS 0 21 Two soap bubble coalesce to form one bubble If decreases in volume and surface area are V and S respectively Atmospheric pressure is P and surface tension is T then correct relation is 3 3 F 3 3P V 4TS 0 4 None of these 22 Two tuning fork when sounded together gives 4 beats per second Frequency of fork A is 248 Hz Now tuning fork Bis waxed due to which beat frequency is increased to 7 beats per second Find the original frequency of B 2 252 Hz 1 244 Hz 3 241 Hz 4 255 Hz For a heat engine the temperature of the source is 127 C To have 60 efficiency the temperature of the sink is 1 160 C 1 F 2 0 6 m s 4 0 7 m s A All N 2 200 C 3 113 C 4 113 C If v is the velocity of an electron in first excited state of H atom and fis the frequency of revolution then the de Broglie wavelength of the electron will be

Test 1 Code A 25 Maximum angular magnification in case of compound microscope is obtained when the fin image is at 1 Least distance of distinct vision 2 Infinity 3 Position of object 4 Focus

Shown in made of a conductor It has inner radius a and outer radius b and carries charge Q At its centre is a dipole p as shown In this case P surface charge density on the inner surface of the shell is zero everywhere b surface charge density on the inner surface is uniform and equal to Q 2 Ana a 8 mC c 6 mC 74 In a certa the z di electric uniform rate of the sys 107 C a c 1 electric field outside the shell is the same as that of a point charge at the centre of the shell d surface charge density on the outer surface depends on IPI mm apurthe electric field at point P oth

A boy runs on a circular path of radius R 28 m with a constant speed u 4 m s Another boy starts from the centre of the path to catch the first boy The second boy always remains on the radius connecting the centre of the circle and the first boy and maintains magnitude of his velocity constant V 4 m s If the time of chase is 10 x sec then x HONDA 22

Choose the correct answer 1 If a physical quantity is given by x and c d the percentage errors of measurement in a b c and d are respectively 2 1 3 and Maximum percentage error in the value of x will be 4 2 3 1 8 3 12 Which of the following curve can t represent 4 motion in one dimension hr 2 If all the pulleys and strings are ideal then the reading of spring balance in given situation is g 10 m s 1 2 edicat JE 3 kg 1 3 kg wt 3 8 kg wt 2 5 kg wt 4 3 75 kg wt A block of mass 2 kg is placed on the flo coefficient of static friction between the ma floor is 0 6 A force F is acting on it as sh the figure The frictional force on the block F 8N 2 kg 5 2 12 N 4 8 N 5 kg 1 Zero 3 2N A ball is dropped from a height of 100 m collision with the floor it loses its 20 energy After collision ball will rise to a heig 1 80 m 3 40 m 2 20 m 4 50 m

A particle moves in a straight line such that its acceleration a varies with speed v as a 2 m s where v is measured in m s If initial velocity is 4 m s then time taken by the particle to come to stop is 2 2 s 4 4 sq 1 2 s VES 3 2 2 s N 124

Example 3 13 All the edges of a block with parallel faces are unequal Its longest edge is four times its shortest edge Find the ratio of the maximum to the minimum resistance between parallel faces

Consider the graph shown in the figure which gives the velocity of an object moving along a line Assume time is measured in hours and distance is measured in miles The areas of three regions bounded by the velocity curve and the t axis are also given Complete parts a through e 13 00 18 10 8 10 a On what intervals is the object moving in the positive direction The object is moving in the positive direction when its velocity is positive Select the correct choice below and if necessary fill in the answer box to complete your choice OA The object is moving in the positive direction on the interval s Type your answer in interval notation Use a comma to separate answers as needed B The object is never moving in the positive direction

Q5 If the total number of H molecules is double that of the 0 molecules then ratio of total kinetic energies of H to that of 02 at 300 K is a 1 1 b 1 2 c 2 1 d 1 16

31 Consider the charges q q and q placed at th vertices of an equilateral triangle of each side The sum of forces acting on each charge is 2 q a b 4 2 01 c 2 q 4 1 q 4 E 1 d zero

A car approaching a crossing at a speed of 30 m s sounds a hom of frequency 500 Hz when 40 m from the crossing Speed of sound in air is 330 m s What frequency is heard by an observer 30 m from crossing on other straight road which crosses car road at right angles 1 539 Hz 3 530 Hz 40m 30m 2 512 Hz 4 550 Hz

A body constrained to move along the z axis of a coordinate system is subject to a constant force F given by F 1 21 3KN where i j k are unit vector along the x y z axis of the system respectively what is the work done by this force is moving the body a distance of 4m along the z axis O 12 J O 10 J O 50 J O None of these

82 If E ds 0 over a a the electric field inside the surface and on it is zero b the electric field inside the surface is necessaril uniform c all charges must be outside the surface d None of these 33 V the Perolls alchype of fnarge in ft Aunive in ind hen there 0 E 0 for out a on on any surface A 2

19 A potentiometer wire of length 1 m has a resistance of 10 Q2 It is connected to a 6 V battery in series with a resistance of 5 Determine the emf of the primary cell which gives a balance point at 40 cm Delhi 2014

If a loop of chain is spun at high speed it can roll along the ground like a circular hoop without collapsing Consider a chain of uniform linear mass density u whose center of mass travels to the right at a high speed v If the loop rolls over a bump the resulting deformation of the chain causes two transverse pulses to propagate along the chain one moving clockwise and one moving counterclockwise A The tension in the chain in terms of u and v is uv B The speed of the pulses traveling relative to the chain is 2v C The speed of the pulses traveling relative to the chain is v D Angle each pulse travels during the time interval over which the loop makes one revolution is 2

A thin flexible chain of uniform mass m and length L is suspended so that its lower end just touches a smooth inelastic fixed plane inclined at 45 It is released at t 0 450 The force exerted by the chain on the plane at time is Assumeris less there falling

A particle is being acted upon by one dimensional conservative force In F x curve shown four points A B C D are marked on the curve for these p F Lov O A and D are equilibrium points OB and C are equilibrium points O A is stable and D is unstable equilibrium point None of these X

A ring of a thin wire of cross sectional area a and length is dipped into a liquid of surface tension o and taken out so that a film of liquid is formed in the ring If young s modulus of material of wire is Y then longitudinal strain developed in the ring will be A lo Y B ay lo o aY D None

Two bodies of masses 10 kg and 2 kg are moving with velocities 21 71 3k and 101 351 3k m sec respectively Find velocity of centre of mass of the syst O 24k m sec O 2k m sec O 401 1401 36k m sec None of these

13 0 Jag If unit of length and time is doubled the numerical value of g acceleration due to gravity will be A doubled C four times D 2010 B havlved D same

Two conducting hollow sphere of radius R and 3R are found to have Q charge on outer surface when both are connected with a long wire and q charge is kept at the centre of bigger sphere Then which one is true A q 2Q B q 3Q C q 4Q D q 6Q

A current carrying power line carries current from east to west The direction of magnetic field at short distance vertically below it is North to South South to North East to West West to East

Graph between power time is given below Then which of the following option is correct for work done by force from t 0 to time t P A First increases till t then decreases till t B First decreases till t then increase till t C Always increases D Always decreases

37 If a ball is thrown vertically upwards with speed the distance covered during the last t seconds its ascent is 1 ut 3 ut 2 5912 2 1 2912 4 u gt t

Three identical wire rings have been placed symmetrically as shown in the figure A B and C are centres of the three rings Resistance of each ring is 3R Find the equivalent resistance of this wire mesh across points C and D 1 C A B D 3 2

Q 99 Three identical wire rings have been placed symmetrically as shown in the figure A B and C are centres of the three rings Resistance of each ring is 3R Find the equivalent resistance of this wire mesh across points C and D 1 C A B D 3 2

7 A projectile is projected in the upward direction making an angle of 60 with the horizontal direction with a velocity of 147 ms After what time will its inclination with the horizontal be 45

The magnetic field between the plates of radius 12 cm separated by a distance of 4 mm of a parallel plate capacitor of capacitance 100 pF along the axis of plates having conduction current of 0 15 A is 1 zero 2 1 5 T 3 15 T 4 0 15 T