Basic Physics Questions and Answers

A river is flowing from west to east at a speed of 5 m min A man on the south bank of the river capable of swimming at 10 m min in still water wants to swim across the river in shortest time He should swim a due north c 30 west of north b 30 east of north d 60 east of north

2 23 Length of steel rod so that it is 5 cm longer than the copper rod at all temperatures should be cm a for copper 1 7 x 10 1 1 x 105 C slom 1 0 105 C and a for steel doss to earn ai

Poil is 30 A coil of effective area 4 m is placed at right angles to the magnetic induction B The e m f of 0 32 V is induced in the coil When the field is reduced to 20 of its initial value in 0 5 sec Find B in wb m

50 x10 0 photons pass through an experimental paratus Part A How many of them land in a 0 150 mm wide strip where the probability density is 22 0 m VA o 2 2 107

3 3 18 x 10 5C m 4 3 18 x 10 10 C m 6 Three charge 4q q and 3q are placed at three vertex 36 of equilateral triangle of side a as shown in figure The dipole moment of system is 4q 1 3qa 3 qa 10 a a 2 2 3 qa 4 qa 13 3 3 18 x 10 5C m 4 3 18 x 10 10 C m figur gang faye d fra faga 1 3qa 3 qa 10 a 4q 2 2 3 qa 4 qa 13

The two identical rectangular steel frames with the dimensions shown are fabricated from a bar of the same material and are hinged Rectangular at the midpoints A and B of their sides 3m x 1m If the frame is resting in the position shown on a horizontal surface with negligible friction determine the velocity v with which each of the upper ends of the frame hits the horizontal surface if the cord D is cut Take the value of dimensions shown in figure c 1 m b 3 2 m and 0 74 i e sin and 0 3 25 04 cos 11 25 A 5 m s C 3 m s g 10 m s b b b A b D C C 0 B side view 0 Smooth horizontal surface B 8 m s D 4 m s

Two charges of 10 C and 10 C are placed at points A separated by a distance of 10 cm What is electric field at a point Por perpendicular bisector of AB at distance 12 cm from its mid point 4 1 x 10 N C 2 1 x 104 N C O 3 2 106 N C 4 5 107 N C

9 One end of a cylindrical rod of glass n 1 5 shown in the figure is given hemi spherical shape of radius GLASS AIR I 4 12 cm 2 0 cm On the left side of this end is placed an object O at a distance of 12 cm Find out the distance v of the image Ans 8 cm

3 6 A 4 8 A 3 6 A 39 Two charged particles having same linear momentum 39 gada describe circular paths of radius R and R respectively in uniform transverse magnetic field If the ratio of their respective charges is 1 3 then the ratio of R and R will be 1 1 3 2 3 1 3 1 9 1 1 3 2 3 1 3 1 9 R fe 1 13 gun

4 A particle is moving eastward with a velocity of 5 m s In 10 s the velocity changes to 5 m s northwards The average acceleration in this time is a zero 1 6 m s towards north east c 30 west of north d 60 east of north

Q 22 The greatest speed of transverse waves through a steel wire of radius 1 mm is x 10 m The breaking stress of steel is 6 0 x 2 3 108 Nm2 Density of steel 7800 kg m m

A uniform chain of length L has one of its end attached to the 3L wall at point A while of the length of the chain is lying on 4 table as shown in figure Find the minimum co efficient of friction between table and chain so that chain remains in equilibrium is 370

is A transparent cube of side a made of a material of refractive index immersed in a liquid of refractive index A ray is incident on the face AB at an angle 8 shown in the 0 figure Total internal reflection takes place at point E on the face BC Then 8 must satisfy a 8 sin H c sin b sin 8 D 2019 Main 12 April 1 d 0 sin V 7 Ho By

In the given figure find the velocity and acceleration of B if velocity and acceleration of A are as shown Choose the correct option A 1m s 2m s A VB 1 m s ag 1 m s B VB 0 5 m s ag 0 5 m s C VB 1 m s ag 0 5 m s aB D VB 0 5 m s ag 1 m s B

A bar of mass m is placed on a plank of mass m which rests on a smooth horizontal plane The coefficient of friction between the surfaces of bar and plank is k The plank is subjected to a horizontal force F depending on time t as F at where a is a constant The moment of time t at which the plank starts sliding is A akg m m m m g ka B D m m kg a ka m m g m m F

The angle between two vectors R 1 i k S xi 31 x 1 k A Is obtuse angle B Is acute angle C Lies between 60 and 120 and

Two velocities of 2 cm s 1 act simultaneously on a particle and are inclined at an angle of 60 with each other Their resultant has a magnitude a 4 cm 8 1 b 3 464 cm 8 1 c zero d some other value

The current in a coil varies with time as shown in figure The variation of induced emf with the time would be 1 T14 emf 44 T 4 T 2 emf T 2 37 4 T14 37 4 T12 3714 t

A pair of parallel horizontal conducting rails of neglig ble resistance shorted at one end is fixed on a smooth table The distance between the rails is L A massless conducting rod of resistance R can slide on the rails frictionlessly The rod is tied to a massless string which passes over a pulley fixed to another edge of the table A mass m tied to the other end of the string hangs vertically A constant magnetic field B exists along the perpendicular to the plane of the table in upward direction If the system is released from rest calculate 1 the terminal velocity of the rod il the acceleration of the mass at the instant when the velocity of the rod is half the terminal velocity Z

A wave is represented by the equation y A sin 10x 15nt n 3 where x is in meters and t in seconds The expression represents 1990 A a wave travelling in the positive x direction with a velocity 1 5m s B a wave travelling in the negative x direction with a velocity 1 5m s C a wave travelling in the negative x direction having a wavelength 0 2m D a wave travelling in the positive x direction having a wavelength 0 2m

Two current carrying loops of same area but of different materials have same current flowing in them in anti clockwise direction if a magnetic field is applied in upward direction then potential energy of loop 1 and loop 2 will always be A Different B Equal C Can be different or equal depend upon material D Can t say

Question No 53 Single Correct A wave of frequency 500 Hz has a velocity of 350 m s The distance between two nearest point on the wave which are 60 out of phase with each other will be around B D 70 cm 0 7 m 12 0 cm 120 0 cm A A Marks 4 00 3 00

Q44 0 3 Marks First Looked X Reflection of the line 1 the plane x y z 7 is B 34 46 A 3 4 4 y 2 X 1 X y 2 84 4 4 3 1 3 Attempted 2 4 1 z 4 1 x 1 y 2 4 2 4 C 1 1 y 2 3 MEDIUM 2 1 in

A rod of mass m and length is placed on a smooth horizontal table An ideal string is tied to the end A of the rod and a point mass m is connected to the other end of the string lies in the horizontal plane Initially the string is made perpendicular to the rod Now an impulse is given to the particle which imparts horizontal velocity v parallel to the rod as shown in fig Just after the impulse is given to the particle the force applied by one half AC of the rod to other half BC of the rod is C mv A 20 2 mv B D mv 10 1 mv B A

13 A capacitor of capacity c is charged to the potential of v On disconnecting with the battery it is connected with a capacitor of capacity c as shown in the adjoining figure The ratio of energies before and after the connection of switch s will be de afa fa fic enfants at sa ar Ref y viena C a fa C V fed GTST TRT at fra m CV a c C C S b c KC C I

In the figure shown A and B are two particles which start from rest A has constant acceleration a the direction shown B also increases its speed at a constant rate b but the direction of velocity always towards A Find the time after which B meets A Also find the total distance travelled by B b a b

A thin glass rod is bent into a semi circle of radius R a charge Q is uniformly distributed along the upper half Vand a charge Q is uniformaly distributed along the lower half The magnitude of the electric filled at the centre of the semi circle is a 2Q 2 ER b Q 2 R C Q 3 R d 2Q 3n ER

A tangent galvanometer has a coil of 50 turns and a radius of 20 cm The horizontal component of the earth s magnetic field is BH 3 10 5 T Find the current which gives a deflection of 45 0 30 A 0 25 A 0 1 A 0 19 A

Drift speed Time needed to drift through 5 cm is 11 123 t j ne 1 106 A m 8 6 x 1028 1 6 x V 5 x 10 mv 2 1 2 3 7 2 x 10 5 The thermal kinetic energy of electrons is of the order of 13 12 KT where K 1 38 x 10 23 J constant KT 3 KT m 5 695 S Distance travelled by electron in t 695 s is 10 19 1 17 x 105 ms 7 2 x 10 5 ms 23 3 x 1 38 x 102 300 9 1 10 31 S vt 1 17 x 105 695 m 8 1 x 104 km Q 48 A copper wire of length 5 cm carries a current of density j 1 A mm 2 The density and molar mass of copper are 9000 Kg m3 and 63 gmol Each copper atom contributes one free electron The temperature of the wire is 27 C Estimate the average distance travelled by a free electron during the time it moves from one end of the

4 200 A 20 The figure shows the number of the remaining nucleus N 20 fift fr of a radioactive source as a function of time t S2 1 L 0 20 40 60 t sec 4 200 A The relationship between N and tis 1 N 1000 e 20 2 N 20e 20 3 N 3 e 0 05 4 N 20 e 0 05 N Of 0 20 1 N 1000 e 20 2 N 20e 20 3 N 3e 10 05 4 N 20e 0 05 40 t sec

Two statements are made regarding three non zero vectors A B and C having different magnitudes 1 Any two of these vectors can be combined to give a zero vector 2 The three vectors can be combined to give a zero vector Then O O O Statements 1 and 2 are always true Statements 1 and 2 are always wrong Statement 1 is always wrong but 2 may be tr

In the circuit shown the capacitor of capacitance C is initially uncharged Now the capacitor is connected in the circuit as shown The charge passed through an imaginary circular loop parallel to the plates also circular and having the area equal to half of the area of the plates in one time constant is fra fr 311 314 enfanfaarger uff 2 Ce 1 11 25 9 di voleu calor for gar 000 E R ww C 1 1 d Zero 4

BEFORE Pivot No torque 50 m s 0 8 m 0 35 00 AFTER 40 m s A baseball of mass 0 15 kg is initially traveling horizontally at 50 m s It is struck by a bat after which the baseball is still traveling horizontally but in exactly the opposite direction from its initial motion at a speed of 40 m s Consider the collision of the bat and the ball Assume that before the collision the bat is moving in a horizontal circle at an angular velocity of rad s Assume that the player holding the bat exerts no torque The bat has a moment of inertia of 0 30 kg m2 about the pivot and the ball hits at a point that is 80 cm away from the pivot After the collision the bat is still swinging in the same direction around the same pivot but with a reduced angular velocity of 0 350 Find the numerical value of 0

In the figure shown A B C D E F are conducting plates each of area A and any two consecutive plates separated by a distance d The net energy stored in the system after the switch S is closed is A B C D E FA aduft S gan and and fagra vufen euf a 3E A 2d V2 c oA v 2d b d 58 A 12 d V E0A V d

1 A vertical rod of length is moved with constant velocity v towards east The vertical component of earth magnetic field is B and angle of dip is 0 The induced e m f in the rod is 1 Blv sin 0 3 Blv cot 0 2 4 B v tan 0 Blv cos 0

A cylindrical magnet is kept along the axis of a circular coil On rotating the magnet about its axis the coil will have induced in it 1 No current 2 A current 3 Only an e m f mf and a ourront

10 A short bar magnet passes at a steady through a long solenoid A galvanometer is connected across the solenoid Which graph best represents the variation of the galvanometer deflection with time t 1 3 S M N 2 4 NS 04

A stone is dropped from the top of a tower towards the earth Another stone is released from the same point exactly one second later What is the separation between the two stones two seconds after the release of the second stone is take g 10 m s O O O 5m 10 m 20 m

A simply supported beam is subjec to a load of w m over the entire span of 2 0 m The cross section is 24 x 50 cm The maximum permissible shear stress is 10 kg cm2 What is the maximum intensity of load that is permissible on the beam a 8000 kg c 16000 kg b 4000 kg d 12000 kg

20 Pa cube 1 cm each side 150 Pa 3 Calculate the upthrust in gf experienced by a 540 g block of aluminium when fully immersed in a water and in b a liquid of density RD 0 9 Relative density of Al 2 7

Which one of the following velocity time graphs does not represent a distance of 2 units 1 iii 0 3 2 0 1 2 t 1 2 ii iv 0 2 0 t 2 2

Q 70 An adiabatic cylinder has length 2 L and cross sectional area A A freely moving non conducting piston of negligible thickness divides the cylinder into two equal parts The piston is connected to the right face of the cylinder with an ideal spring of force constant k The right chamber contains 28 g nitrogen in which one third of the molecules are dissociated into atoms The left chamber container 4 g helium With piston in equilibrium and spring relaxed the pressure in both chamber is Po The helium chamber is slowly given heat using an electric heater H till the piston moves 3L to right by a distance Neglect the volume occupied by 4 the spring and the heating coil Also neglect heat capacity of the spring a Find the ratio of Cp and Cy for nitrogen gas in right chamber b Calculate change in temperature of helium c Calculate heat supplied by the heater LK Helium H 00000 L k www Nitrogen

The velocity of a body moving with uniform acceleration is 10 m s at a particular instant Its velocity after 5 second is 20 m s What was the velocity of the body 3 second before that instant O O O 2 m s 4 m s 6 m s 8 m s

A vector P when added to the sum of the vector 21 31 k and 31 k gives a unit vector along the x axis What is the magnitude of the vector P O O O 12 20 24

On planet M a stone of mass 200g takes 4s to reach the bottom when dropped from a height of 50m Calculate the acceleration on the surface of the planet and hence find the weight of the stone in N TO VACULUM PA

plane as allel and hassless me frame the rod is ard which ulley A upward constant ventually 0 26 An arrangement of smooth pair of long conducting rails which are resistanceless are joined to a charged capacitor The rails are connected by a rod of mass m and length and resistance R Vertical magnetic field is uniform The rod is initially at rest It starts moving due to the influence of magnetic field What should be the mass of the rod in mg so that its kinetic energy in steady state is maximum Take 1m B 2T C 1 F R 192 A mass m JE PHYSICS Q 5 Q 6 The self produced em current in it is changed in Is the change in 1 740 J 3 540 J There are two long or The inner and outer c of turns per unit le ratio of mutual indu the inner coil is 1 3 11

4 Light from our first door neighbouring star reaches us in 4 5 year Calculate its distance from earth in kilometre Velocity of light is 3 x 108 m s 1 Take 1 year 365 days Ans 4 257 x 1013 km

A ship X moving due north with a velocity v observes that another ship Y is moving due west with velocity v The actual velocity of Y is A v due east B 2v towards northwest C v towards southeast D 2v towards northeast

A particle moves with a velocity 51 31 6k m s under the influence of a constant force F F 101 10 20k N What is the instantaneous power applied to the particle O O O 200 W 140 W 100 W

The charge flowing through a conductor beginning with time t 0 is given by the formula Q 4t 2t nt coulombs Find the dq dt current i at the end of the 2nd second A 11 5 amp C 13 5 amp B 12 5 amp D 14 5 amp