Basic Physics Questions and Answers

Given the velocity function v t 5cost 5sint 2t a Find the position function wherer 0 0 0 7 Answer b Find the magnitude of the net force of the object if the mass is 10 kg with the given velocity func Hint F ma Answer F to the nearest two decimal places

A shell explodes in a region of negligible gravitational field giving out n fragments of equal mass m Then its total 1 Kinetic energy is smaller than that before the explosion 2 Kinetic energy is equal to the before the explosion 3 Momentum and kinetic energy depend on n 4 Momentum is equal to that before the explosion

Two blocks of masses 10kg and 4kg are connected by a spring of negligible mass and are placed on a frictionles horizontal surface An impulse gives a speed of 14 ms to the heavier block in the direction of the lighter block The the velocity of the centre of mass is 1 30 ms 1 2 20 ms 3 10 ms 4 5 ms

2 486 J 3 524 J 4 324 J A shell of mass 200 g is ejected from a gun of mass 4 kg by an explosion that generates 1 05 kJ of energy The ini velocity of the shell is AIPMT 200 1 100 ms 2 80 ms 3 40 ms 4 120 ms

Q5 The figure gives the free body diagram when several forces act on an object pulling it along a frictionless flat floor What will be the direction of acceleration of the object 7N 2N y SN AN O A x direction O B y direction O C y direction O D x direction SN

Mark correct option or options 1 Mutual gravitational attraction between two bodies can be considered as impulsive force during collision 2 Collision is process in the absence of impulsive force 3 During collision momentum of system may change 4 Mutual gravitational attraction between two bodies cannot be considered as impulsive force during collis

For total internal reflection to occur which of the following is correct Light travels from rarer to denser medium Light travels from denser to rarer medium Light travels in air only Light travels from any one medium to any other medium

0 The equivalent capacitance between the terminals X and Y in the figure shown will be 1 100 pF X 200pF 200pF 100pF Y 2 200 pF 100pF 100pF 100pF 3 300 pF 4 400 pF

15 Due to a point charge potential and electric field at a point A are 7 V and 3 V m respectively and electric field at a point B is less than 3 V m Now magnitude of the charge is tripled If electric field at B becomes 3 V m potential at B will become closest to a 7 V c 21 V b 12 V d Insufficient information

11 A solid cube is subjected to equal normal forces on all its faces The volumetric strain will be x times the linear strain in any of the three axes when a X 1 b X 2 c X 3 d X 4

Q15 The pressure inside a commercial airliner is maintained at 1 00 atm 105 Pa What is the net outward force exerted on a 1 0 m x 2 0 m cabin door if t outside pressure is 0 30 atm O A 140000 N O B 140 N O C 1400 N O D 14000 N

6 In a YDSE distance between the slits is 2 mm the distance of the screen from the slits is 1 m and the wavelength of light used is 5000 A The fringe width is 1 0 25 cm 3 0 25 mm 2 2 5 cm 4 1 5 mm

A chain of mass m forming a circle of radius R is slipped on a smooth round cone with half angle 0 Find the tension in the chain if it rotates with a constant angular velocity o about a vertical axis coinciding with the symmetry axis of the cone A R gcot 8 C R g cot 8 B Rg cot D Rwg cot

In given two cases two concentric conducting spherical shells are arranged as shown In case 1 when switch S is closed energy loss is Q In case 2 when switch S is closed energy loss is Q then find Q Q in Joule Assume q 2 C r 10cm Neutral 2r 9 Case 1 S 2r q Neutral Case 2

31 Three polaroids P P2 and P3 are kept such that P and P3 are crossed and if the angl between the pass axes of P2 and P is 37 and the intensity of unpolarized light incident o P is Io then the intensity of light coming ou of P3 will be nearly 1 111 810 25 3 0 P 2 4 1610 25 7210 625 P3

A charge q is placed at the corner of a cube of side a The electric flux through the cube is Zero 9 380 9 680 9 880

An inventor claims that when temperature of source and sink are 127 C and 27 C respectively then efficiency of engine is 26 then 3127 27nd and af sig 26 at A It is impossible B It s possible but possibility is less 46 47 4 C It s possibility is high D Data is insufficient Kics i Your Answer C

pher 20 Consider a thin conducting shell of radius r carrying total charge q Two point charges q and 2q are placed on points A and B which are at distances 0 5r and 2r from the centre C of the shell respectively If the shell is earthed how much charge will flow to the earth a 2q c 4q b 3q d More than 2q and less then 3q 0 5r 2r

27 During a short interval of time the velocity v in meters per second of an automobile is given by v at bt where the time t is in seconds The units of a and b are respectively A s m s m B m s m s3 c m s m s D ms2 ms4 Marks

14 A sample gas expands from volume V to V Amount of work done by the gas is greatest when expans A Equal in all cases B Isobaric c Isothermal m Adiabatic

A straight chain consisting of n identical metal balls is at rest in a region of free space as shown In the chain each ball is connected with adjacent balls by identical conducting wires Length of a connecting wire is much larger than the radius r of a ball A uniform electric field E pointing along the chain is switched on in the region Find magnitude of induced charges on one of the end ball a 2m n E b 2 r n 1 IE c 4r n 1 IE d 4 ms n 1 FE

23 Electrostatic potential V at a point on circumference of a circular layer of uniform charge and radius r is given by equation V 4or here o is surface charge density in the layer Which of the following expression correctly represents electrostatic energy stored in the electric field of a similar charge layer of radius R a R c no R3 b R d R

A conducting wire having cross section area 1 0 mm and length 1 0 km The wire resistivity is 10 2 m at 20 C and its resistance is 2 0 2 at T 320 C Find the temperature coefficient of resistivity in C 1 of the material 1 10 0 x10 3 2 05 0 x10 3 03 3x10 3 4 025 x10 3 5 02 0x10 3

1 2 F 2 4 F 3 6 F A 40 F capacitor in a defibrillator is charged to 3000 V The energy stored in the capacitor is sent through the patient during a pulse of duration 2 ms The power delivered to the patient is AIIMS 2004 1 45 kW 2 90 kW 3 180 kW 4 360 kW pocitors each of capacitance value C are connected as shown in the figure The ratio of capacitance between P TAIIMS 2006

1 1 2 2 A parallel plate condenser with a dielectric of dielectric constant K between the plates has a capacity C and is charged to a potential V volts The dielectric slab is slowly removed from between the plates and then reinserted The net work done by the system in this process is AIEEE 2007 1 K 1 CV 3 K 1 CV 4 zero pon the plates has a capacitance of 9 pF The separation between its plates 2 CV K 1 K

1 45 pF 2 40 5 pF Let C be the capacitance of a capacitor discharging through a resistor R Suppose t is the time taken for the energy stored in the capacitor to reduce to half its initial value and t is the time taken for the charge to reduce to one fourth its initial value Then the ratio t t will be AIEEE 2010 1 1 2 1 2 3 1 4 4 2

44 Velocity time graph is given for a object moving along a straight line then distance covered by the particle in to sec will be slope of graph is a v Ao 1 fore 2 v to at 4625 V V 60 2 CET B V Both are correct 4 None vito T V V to 2 mis a tyto 2 at Spul 2 S 14 5 4

H 4 P is best Q worst Two thermometers are used to record the temperature of a room If the bulb of one is wrapped in wet hanky 1 The temperature recorded by both will be same 2 The temperature recorded by wet bulb thermometer will be greater than that recorded by the other The temperature recorded by dry bulb thermometer will be greater than that recorded by the other 4 None of the above

Q In a dispersive medium the phase velocity u is a u is a function of b u is a not a function of c u is a function of d None of the above

Zero Marks Negative Marks 1 If none of the options is chosen i e the question is unanswered In all other cases The capacitor in the figure has C 10 F and distance between the plates d 1mm when the switch was open Now with the switch closed the distance is reduced to 0 8d with the attached plate at equilibrium Assume left plate is fixed and the spring was initially in relaxed state If E 4volts then the spring constant K is equal to C 10uF K m

are A wave pulse is generated in a string that lies along x axis At the points A and B as shown in figure if R and R ratio of wave speed to the particle speed respectively then 1 R Rg 3 R R A B Vp slope Uwave 1 slepe V way Up SAZSB sloped A 2 R RA 4 Information is not sufficient to decide to the right without changing shape Consider two particles at

20 The following figure depicts a wave travelling in a medium Which pair of particles are in phase 1 A and D 2 B and F B wave depends E 3 C and E G 4 B and G

A uniform spherical ball of radius r and mass m is dropped into a lake having liquid of density one third of density of ball and viscosity n Choose INCORRECT statement for steady state having terminal speed UT O Drag force at steady state is mg O Gravitational potential energy is getting lost at rate mgur at steady state Heat produced at rate mgur at steady state O Ball gains approximately 63vT 100 speed after time t 6 m

We know moving charges are what produces an electrom agnetic field But we know the particles of light are photon s and that photons have no charge Then how can light pro duce an electric and magnetic field and hence how can it be considered as an electromagnetic wave

Two coherent sources are separated by a distance d 2A are placed at the centre of a large circular screen arranged symmetrically as shown R is radius circular screen R d Light of wavelength A is used in the experiment How many bright fringes will be observed on screen from A to B first quadrant Y axis S B 02 03 S A Circular screen d 2 X axis

4 Maximum displace There are some points in a stationary waves which 1 Are never at rest 2 Are always in motion 4 Are at rest once in each cycle 3 Are at rest twice in each cycle Actretched string of length L fixed at both ends can sustain stationary waves of wavelength give

Two equal masses are situated at a separation ro One of them is imparted a velocity vo ind the ratio of maximum and minimum separation between them Gm To perpendicular to the line joining them both are free to move Treating motion only under mutual gravitational forces

Consider the following statements 1 XeO3 is a colourless explosive solid 11 XeOF4 is a colourless volatile solid III lonization enthalpy of molecular oxygen is identical with xeno Choose the correct statements O I II and III OII and III only OI and III only OI and II only

A bulb is placed at depth of 2 7 m in water and a floating opaque disc is placed over the bulb so that bulb does not appear visible from the surface The minimum radius of the disc is w 4 3 06m O 2 7m O 4 9 m 12 m

A charged particle q is placed inside a grounded metallic shell of inner and outer radii a and h respectively as shown in the figure The particle is at a distance of magnitude of potential at the center of the sphere is equal to I 1 4m o Lb 1 191 4mo la 1 47 o a CE L 9

A monoatomic gas undergoes a polytropic process which is defined by expression PV3 constant The molar specific heat capacity of the gas will be R is universal gas constant OR O2R O 3R

Section A Q 1 When white light enters a prism it gets split into its constituent colors This is due to a Different refractive index for different wavelength of each color b Each color has same velocity in the prism c Prism material have high density d Scattering of light

A graph is drawn between force acting and time for which it acts on particle The area under the curve between time interval t and to giv Momentum of particle Force acting on particle Change in momentum of particle Acceleration of the particle

1 2 2 4 3 5 In periodic table if elements n 5 does not exits then total number of elements will be L 50 2 60 3 110 4 182 According to Bohr s model of hydrogen atom relation between principal quantum number n and

Two metallic sphere rland r2 are touched and separated f ind the ratio of their self energy For this how are they ge tting U kq 2 2r by 2r shouldn t it just be by r aka ii iii Q iv Q V V V 2 r 165 U Q 4 Disions of Aakash ucatio 2 E KQ 2r KQ2 2 1 KQ 12 JEE

25m 46 Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state 51 irradiates a photosensitive material The stopping potential is measured to be 3 57 V The threshold frequency of the AIPMT Pre 2012 materials is 1 4 x 10 5 Hz 2 5 x 10 5 Hz 63 1 6 x 1015 Hz 4 2 5 x 10 5 Hz liug 083 cm in the presence of a magnetic field of 0 25 Wb m The

TV1 2 An electron of mass m with an initial velocity v viv 0 enters an electric field E Ei E constant 0 at t 0 If is its de Broglie wavelength initially then its de Broglie wavelength at time t is NEET 2018 4 2 Ap 1 E my 2 A 1 1 mv 3 At hit of the hydrogen atom is NEET 2018

Relation between wavelength of photon and electron of same energy is 1 ph G 2 ph c 4 3 ph then value of n I m s will be ph constan

The wavelength involved in the spectrum of deuterium D are slightly different from that of hydrogen spectrum because 1 size of the two nuclei are different 2 nuclear forces are different in the two cases 3 masses of the two nuclei are different 4 attraction between the electron and the nucleus is different in the two cases 17 the energy required to remove the electron from the

Light of wavelength 500 nm is incident on a metal with work function 2 28 eV The de Broglie wavelength of t emitted electron is NEET 201 1 2 8 x 109 m 2 2 8 x 10 12 m 3 2 8 x 10 10 m 4 2 8 x 109 m