Basic Physics Questions and Answers

Example 13 1 Given the mass of iron nucleus as 55 85u and A 56 find the nuclear density Solution mre 55 85 u 9 27 10 26 kg Nuclear density www 1 56 mass 9 27 10 26 volume 4 3 1 2x10 15 2 29 x 10 7 kg m The density of matter in neutron stars an astrophysical object is comparable to this density This shows that matter in these objects has been compressed to such an extent that they resemble a big nucleus www

SOLVE A tennis ball hit vertically upward has an initial velocity of 8m s The height y reached by the ball after x seconds is denoted by y 8x x What values of x is the object at or above a height of 15m 1

Based on experimental observations the acceleration of a particle is defined by the relation a 0 1 sin x b where a and x are expressed in m s and meters respectively Knowing that b 0 8 m and that v 1 m s when x 0 determine a the velocity of the particle when x 1 m b the position where the velocity is maximum c the maximum velocity

position at t 0 13 Figure 5 42 shows the position of a medium particles at 1 0 supporting a simple harmonic wave travelling either along or opposite to the positive x axis y cm 10 S 5 10 1 2 3 P 456 0 78 9 10 11 12 13 14 15 16 x m X Singl Fig 5 42 a Write down the equation of the curve b Find the angle made by the tangent at point P with the x axis 1 T 3 c If the particle at P has a velocity v m s in the negative y direction as shown in figure then determine the speed and direction of the wave 2 d Find the frequency of the waves e Find the displacement equation of the particle at the origin as a function of time displacement equation of the wave

BEGINNER S BOX 1 Gas constant R has dimensions Use PV nRT P Pressure V Volume T Temperature n umber of moles A MULT21 11 1 R M1L2T 21 1 1 1 M 11 2T 217 1 1 1 D M1L 1T2K1 H

Calculate the ratio of number of surface atoms versus bulk atoms in three separate particles that are different in their diameter at least 10 4 times The smallest particle should be at least 100 times the size of the atoms

rge Q ace of 60 plate am neetquestion aper then erial then thin rod is bent into a semi circular arc of radius R The rod has a uniform linear charge density 2 The potential at the centre of the arc point P is tial 2 1 2 ER 2 R 2 450

0 Consider a ray of light incident from air into a slap glass refractive index n of width d at an angle The phase difference between the ray reflected the top surface of the glass and the bottom surface INCERT Exempl a b c 4 nd 4nd 2 7 sin sin e 0 1 2 And 1 sin 0 X d 4d 1 sin 8 0 I 2 2

In an experiment to measure the focal length f of a concave mirror the object distance x and image distance y measured as 24 0 0 1 cm and 12 0 1 1 1 0 1 cm respectively then x y Absolute error in focal length is 0 2 cm Percentage error in focal length is 1 7 Percentage error in focal length is 0 7 Percentage error in measurement of object distance is 0 4

65 A positive charge is moving under the effect of a uniform electric field alone It moves from potential zone V to potential zone V V V Its speed 1 Increases 2 Decreases 3 Remains constant 4 Will become zero at V

generated at one end x 2 A transverse harmonic wave of amplitude 0 01 m is 0 of a long horizontal string by a tuning fork of frequency 500 Hz At a given instant of time the displacement of the particle at x 0 1 m is 0 005 m and that of the particle at x 0 2 m is 0 005 m Calculate the wavelength and the wave velocity Obtain the equation of the wave assuming that www

The work done in moving a particle from a point 1 1 to 2 3 in a plane in force field with potential U k x y is x y 1 y 2 3K k 1 3k 2 3k 3 k 4 Zero 7 A ball 100 gm thrown from ground with speed to the ground with speed

44 A triangular 90 rests block of mass M with angle 30 60 with its 30 90 side on a horizontal smooth fixed table A cubical block of mass m rests on the 60 30 side of the triangular block What horizontal acceleration a must M have relative to the stationary table so that m remains stationary with respect to the triangular block M 9 kg m 1 kg A 2 8 m s C 8 4 m s B 5 6 m s D Zero

12 By the side of a lake the mercury in a barometer stands at 75 cm Mercury used in the barometer 40 has specific gravity of The volume of an air 3 bubble increases by 50 while travelling from the bottom to the top of the lake The depth of the water lake is approximately 1 5 m 2 70 2 10 m

9 mg 0 Uniform E field As shown in the figure a ball with a mass of 0 810 g and positive charge of q 42 7 C is suspended on a string of negligible mass in a uniform electric field We observe that the ball hangs at an angle of 15 00 from the vertical What is the magnitude of the electric field in N C

48 A scooterist sees a bus 1 km ahead of him moving with a velocity of 10 m s With what speed the scooterist should move so as to overtake the bus in 100 s b 20 m s 1 a 10 m s c 50 m s d 30 m 8 1 19 A body A is projected upwards with yelocit

nsider a wire placed along z axis and having current along z axis it fad along the path PRO shown in figure is then find the value of K

D On a two lane road car A is travelling with a speed of 36 km h Two cars B and C approach car A in opposite directions with a speed of 54 km h each At a certain instant when the distance AB is equal to AC both being 1 km B decides to overtake A before C does What minimum acceleration of car B is required to avoid an accident a 9 8 ms c 1 ms b 10 ms 2 d 2 0 ms 2

How can the answer be option 3 Can t it be written as c dlog a b like the other log functions If that is possible then why is it inco nsistent A B C and D are all dimensionally different Then which of the following must be inconsistent X AB CD eAB sin CD log AD B A C

4 74 A particle accelerated by a potential difference V flies through a uniform transverse magnetic field with induction B The field occupies a region of space d in thickness Prove that the angle a through which the particle deviates from the initial direction of its motion is given by 9 2Vm where m is the mass of the particle sin dB

The adjoining curve represents the velocity time graph of a particle its acceleration values along OA AB and BC in metre sec are respectively a 1 0 0 5 b 1 0 0 5 c 1 1 0 5 d 1 0 5 0 Velocity m sec 10 5 O A 10 B 20 30 40 Time sec

9 Assertion A If A B C D are four points on a semi circular arc with centre at O such that AB BC CD then Reason R AB AC AD 4AO OB OC Polygon law of vector addition yields AB BC CD AD 2AO D B C In the light of the above statements choose the most appropriate answer from the options given below ons 1 A is correct but R is not correct 2 Both A and R are correct and R is the correct explanation of A 3 Both A and R are correct but R is not the correct explanation of A 4 A is not correct but R is correct

17 A point object is moving on the principal axis of a concave mirror of focal length 24 cm towards the mirror When it is at a distance of 60 em from the mirror its velocity is 9 cm sec What is the velocity of the image at that instant 1 5 cm sec 3 4 cm sec 2 12 cm sec 4 9 cm sec

4 0 6 0 CE0109 minals of m on the hen 5 2 cell the stance 5 210 and ce en YE 3 10 4 50 CE0115 The following diagram shows the circuit for the comparison of e m f of two cells The circuit can be corrected by F E E E www B 1 reversing the terminals of E 2 reversing the terminals of E 3 reversing the terminals of E 4 reversing the current in R T 1 E E 3 E E 1 00 A resistan and resis connect resista identi of the CE0116 and

23 An iron rod of 0 5cm area of cross section is subjected to a magnetising field of 1200 A m If susceptibility of iron is 599 calculate i u ii B and iii p magnetic flux produced 0 905T 4 525x105 Wb 7 54x10 4Tm A

65 Cu Natural copper occurs as a mixture of two isotopes The isotope Cu has relative abundance of 70 whereas the isotope 29 has an abundance of 30 The atomic mass of natural copper is A 63 B 63 6 C 64 3 D 65 63 29

In this question Find the local maxima and minima for the function y x 3 3 X 21 got answers 6 and 6 for minima a nd maxima respectively but the real an swers are 1 and 1 how it is 1 and 1 can u explain sir or mam

A sample of hydrogen atom gas contains 100 atoms All the atoms are excited to the same nth excited state The total energy released by all the atoms is Rch where Rch 13 6 eV as they come to the groun state through various types of transitions 4800 49 48 A Maximum energy of the emitted photon is 49 B Initially atoms are in 6th excited state C Initially atoms are in 7th excited state Rch DI Maximum total number of photons that can be emitted by this sample is 100

A uniform chain of mass M and L is attached the vertical wall so that exactly half of its length is resting over rough horizontal surface and half of length is hanging If tangent drawn at the point P in the chain makes an angle 37 with vertical as shown in figure then frictional force acting on the chain is 1 3 Rough surface 3Mg 8 Mg 2 2 4 37 Vertical wall Mg 8 4Mg 5

Question 28 A 180 metre long train is moving due north at a speed of 25 m s A small bird is flyingdue south a little above the train with a speed of 5 m s The time taken by the bird to cross the train is a 10 s b 12 s

An ideal gas takes part in two thermo dynamical processes in which it is heated from the same initial state to the same final temperature The process are shown on PV diagram by straight line 1 and 2 MN is an isothermal curve A Change in internal energy in process 1 and 2 is equal B WAB WAC C Heat exchange in process AC is more than heat exchange in process AB P P B D Work done in process AC is more than work done in P process BC A V 1 N B 2 C

Two persons standing on a frictionless surface throw a ball back and forth between them Which statements ue A The interaction mediated by the ball is repulsive B If we film the action and play the movie backward the interaction appears attractive C DI The total momentum of the two persons and ball is conserved The total mechanical energy of the two people is conserved

A ball is thrown vertically upwards from the ground It crosses a point at a height 25 m twice at an interval of 4 sec Find the initial velocity of ball g 10 m s A bird moves from point 1 2 to 4 2 If the speed of the bird is 10 m s then the velocity vector of the bird is ai bj m s then find product of a and b

acting at B pulls this system with an acceleration of 2m s Find the tension in the string in newton A boat is traveling east at 12 m s A flag flaps at 53 N of W at the bow of the boat Another flag on shore flaps due north Find the speed in m s of the wind as measured on land A ball is thrown vertically upwards from the ground It crosses a point at a height 25 m twice at an interval of 4 sec Find the initial velocity of ball g 10 m s

Make your own word problem about uniformly accelerated motion One 1 for horizontal motion and another one 1 for free fall Show your illustrations and complete solutions to the problems Be sure that the problems are not taken from the internet and that they are realistic RUBRICS Criteria Description Given is complete which means that it has variable s and magnitude with units Unknown required variable s is are identified Equation s or derivation is correct Correct substitution of values Correct final answer Problem is realistic Total Points 2 1 1 2 1 3 10

interval of 4 sec Find the initial velocity of ball g 10 m s A bird moves from point 1 2 to 4 2 If the speed of the bird is 10 m s then the velocity vector of the bird is ai bj m s then find product of a and b For motion of an object along x axis the velocity v depends on the displacement x as v 3x 2x What

Question 36 A scientific theory a cannot be changed but can be reformulated b is fixed once and for all because it is logical c is changed to suit new fashion among scientists d can be revised if required to fit new phenomenon or da

A string has resonant frequencies given by 1001 Hz and 2639 Hz A If the string is fixed at one end only 910 Hz can be a resonance frequency B If the string is fixed at one end only 1911 Hz can be a resonance frequency C If the string is fixed at both the ends 364 Hz can be one of the resonant frequen 1001 Hz is definitely not the fundamental frequency of the string D

A train is moving with uniform velocity on a straight track A boy moving at 4 km h due east observes that the train is moving due north Another boy moving at 1 km h due south claims that the train is moving towards north east What is the speed of the train in ground frame

Which of the following statements is wrong about a ball thrown vertically up A It is moving with constant acceleration B It may have different velocities at the same position C It may have two positions at the same time D The angular momentum of particle about point of projection remain conserved 1 only C 2 C D 3 B C D 4 A B C D

fel 9 A man is hanging from the free end of a massless rope of length 40 m The mass of the man is 204 kg and the maximum tension that the rope can bear in 300 N Then starting from rest the minimum time in which man can reach the other end of the rope is g 10 m s 24s 1 30 3 40 A blo surfac maxic m 5 a 300 the b 1 2 s 3 6 s 4 8 s 30 A small block m is placed on another block of ble 16 A constant horizontal a 33

13 In the arrangement shown all surfaces are frictionless and pulley and string are ideal The maximum value of F so that the blocks remain at rest with respect to wedge is 1 1 3Mg 3 2 5Mg M 30 3M M 2 1 6Mg 4 3Mg F

MMX My and the daughter nuclei respectively in a radioactive decay The Q value of decay is Q and that for decay is Q2 If me is mass of an electron then which of the following is correct Q Mx My c Q My My c

C 1 90 A car 2 m long and 3 m wide is moving at 13 m sec when a bullet hits it in a direction making an angle 0 tan 3 4 with the car as seen from the street The bullet enters one edge of the corner and passes out at the diagonally opposite corner Neglecting any interaction between bullet and car find the time for the bullet to cross the car A 0 25 sec C 0 15 sec 3 m V 2 m Figure 1 134 Vcar 13 m s B 1 3 sec D 0 6 sec 1 9 the bac an ift

P and Q are two forces of equal magnitude acting at a point O at such an angle that their resultant R has a magnitude equal to that of P If the magnitude of P is doubled then find the angle in degree between the new resultant Rand 2

15 A train can cross a platform in 97 2 seconds and a person on bicycle is running with speed of 15 km h in same direction as that of train in 54 seconds Find the time taken by another person to cross the platform whose speed is twice of the person on bicycle and length of platform is same as that of train 97 2 s faen 15 fafter 3 54 sats for fragt a 14 86 seconds b 11 62 seconds c 11 92 seconds d 13 43 seconds el None of these

how to know if we should use 2n 1 or 2n 1 In Young s double slit experiment two slits are separated by 0 1 mm and they are 0 5 m from screen The wavelength of light used is 500 nm The distance between 7th maxima and 11th minima on screen is 1 6 7 mm 3 5 2 mm 2 4 3 mm 4 8 75 mm

A conservative force F 4x 8 i N associated with this force is assigned a value of 8 J at x 0 Which of the following best represents variation in potential energy with position coordinate x A C 20 400 10 soquer 10 6xim 4 xon B D 4 20 ULD troxt N 20 10 UL 5 4xim

Eight point charges having magnitude q are fixed at vertices of a cube The electric flux through square surface ABCD of the cube is 1 2 3 q 24 0 q 12 0 q 6 0 A q q D q E q H q B q G q Your Answ

4 A particle is thrown vertically up with speed us that distance covered in last second of flight 35 m If g 10 m s then initial speed of throw 1 20 m s 2 30 m s 3 40 m s 4 50 m s