Basic Physics Questions and Answers

The density of copper is 9 10 kg m and its atomic mass is 63 5u Each copper atom provides one free electron Estimate the number of free electrons per cubic meter in AMU Engg 2010 copper a 10 9 c 1025 b 1023 d 1029

The charge q in a spherical region of radius 2e 3t The ini changes with time t as q current density at the surface of spherical region 1 3 2 R A s 2 2 3 R A s

The figure shows a hexagonal swimming pool A person standing at point A on ground wants to reach point B see figure in least possible time The person can move with a speed V on ground and with a speed in pool Find the least possible time in which the person can go from A to B Given OA OB 5e A C 2 5 V 4 20 V B D 3 2 V 2 5 28 V V5 F31 60 B

12 Fig 13 47 shows a wire of length and I and of slightly R non uniform cross section Its radius at one end is R and at the other it is R The wire is stretched by forces F and F applied along the length in opposite directions and normal to the ends Y being the Young s modulus extension caused in the wire is nearly Fl FIY TYR R FIY TR R a c b d 1 Fig 13 47 R R R FY I R R hau

The carbon resistor has orange bands The maximum value of resistance offered by the resistor will be GUJCET 2014 a 49 9 KQ b 39 6 KQ c 33 KQ d 26 4 KQ

In the absence of applied potential the electric current flowing through a metallic wire is zero because VITEEE 2008 a The electrons remain stationary b The electrons are drifted in random direction with a speed of the order of 10 2 cm s c The electrons move in random direction with a speed of the order close to that of velocity of light d Electrons and ions move in opposite direction

oose a Time period of a simple pendulum depends on amplitude b Time shown by a spring watch varies with acceleration due to gravity g c In a simple pendulum time period varies linearly with the length of the pendulum d The graph between length of the pendulum and time period is a parabola

9 a Show that the de Broglie wavelength for a relativistic particle of rest mass mo and charge q accelerated from rest through a potential difference of V volts is given by h 2moqv 1 V zmoc b What voltage must be applied to an electron microscope to produce electrons of wavelength 0 40 c What is the de Broglie wavelength of an electron moving with a velocity v d Calculate the de Broglie wavelength of an electron having energy 104 eV and compare with wavelength of electromagnetic radiation for which photons have that same energy

1 For simply supported beam having point load W N at centre support reactions are O o Equal Unequal O Can t say 2 Given UDL can be converted in to equivalent point load using relation O UDL Eq point load UDL Eq point load length O Eq point load X length Eq point load length 2

Two independent SHMS along y axis whose equations are y 6 4 Sin wt and y 3 Cos wt are superimposed on a particle Find out amplitude of resultant SHM 1 5 3 7 2 11 4 109

1 A ball thrown from the top of a building with a velocity of 20 0 m s at an angle of 37 above the horizontal reaches the ground after 7 0 s Find a the height of the building b the horizontal displacement distance between the bottom of the building and the point at which the ball hits the ground of the ball c the maximum height reached by the ball 5 5 5 AY 20 0 s 370

22 A cantilever AD 1 5 m long carries point loads of 500 N 700 N 900 N at 0 5 m 1 mand 1 5 m from fixed end A respectively Support reaction at A will be O 1200 N O 2200 N O 1500 N O 2100 N 23 Refer data in example 22 According to your calculations Maximum value of shear force is O 1200 N O 2200 N O 1500 N

d A power station generates electricity at 120 MW and 112500 V The electricit is carried along cables with resistance of 14 02 i What is the current through the cables 1 1x1 3 A 1 1x104 A 9 374x10 4 A 1 35x1013 A ii What is the power loss in the cables 3584 MW 225 128 MW 1575 1575 MW 128 225 3584 MW

Two identical springs are connected to mass m as shown K spring constant If the period of the configuration in i is 2 sec the period of the configuration in ii is www Leggea 3 Leeeee M i 1 2 2 sec 111 1 2 sec eeeeeeeee 2 1 sec M ii 4 2 sec 1000000000

A parachutist after bailing out falls 50 m without friction When parachute opens it decelerates at 2 m s He reaches the ground with a speed of 3 m s At what height did he bail out 1 91 m 2 182 m 3 293 m 4 111 m A car moving with a speed of 50 km hr can be stopped by brakes after at least 6 m if the same car

In a constant pressure calorimeter with heat capacity 6 65 J K1 0 500 g of Zn reacts with 100 mL of 1 0 M HBr Assume that the solution has the same properties as water If the temperature of the system increased by 5 61 C what is the enthalpy of the reaction per mole of limiting reactant O 412 kJ mol 1 O 389 kJ mol 1 313 kJ mol 1 455 kJ mol 1

This section contains 35 SINGLE CORRECT TYPE questions LS 69 If 9 divisions of main scale are equal to 10 divisions of Vernier scale and given that one main scale division is equal to a units then the least count of Vernier caliper is 818 0 100 Read More

In a coupled system of two pendulums bobs of mass 50 gm each are suspended by mass less rigid rods In in phase mode of oscillation the frequency of oscillation is 0 56 Hz The length I of each pendulum is O122 8 cm 79 2 cm 914 cm

1 A train moves in north direction with a speed of 54 km h A monkey is running on the roof of the train against its motion with a velocity of 36 km h with respect to train The velocity of monkey as observed by a man standing on the ground is

The initial stage of star formation is a free fall collapse This switches over to a more gradual collapse when nuclear fusion begins in the core of the cloud hydrogen in the cloud is completely ionized convection sets in below the surface of the young star the cloud becomes opaque to its own radiation 71

In the circuit the internal resistances of the batteries are 0 12 2 and 0 08 2 Calculate i current in load ii current supplied by each battery by superposition method Ans I 8 9A I 13 06A 41 13

12 The momentum of a particle is P A Bt Where A and B are constant perpendicular vectors The force acting on the particle when its acceleration is at 45 with its velocity is a 2 A B c zero B b 2 B d 2 A

d There is an electrostatic force of 2 4x10 16 N on an electron moving between two metal plates The potential difference between the plates is 150 V The charge on an electron 1 6x10 19 C i What is the separation of the plates 0 0225 m 0 225 m 0 1 m 10 m ii What is the electric field strength 1500 Vm 666 7 Vm 1 0 07 Vm

iii Can a thin film of MgF2 of refractive index 1 22 act as antireflection film if deposited on the surface of glass of refractive index 1 52 If yes determine the minimum thickness required to cut of reflection due to wavelength of 5500

The resultant of two vectors is perpendicular to one of them and has the magnitude 4 m If the sum of the magnitude of two vectors is 8 m then their respective magnitude are 1 4 m 4 m 3 3 m 5 m 2 2 m 6 m 4 1 m 7 m

If the earth sun distance is held constant and the mass of the sun is doubled then the period of revolution of the earth around the sun will change to A 2 years C years B D 1 ye 2 years years

Given Mass of the car m Speed of the car v 40 km h Radius of the circular road r We know that when v rg tan the car will turn without skidding even when there is no frict So option A is incorrect Also in the absence of friction we know that if the car moves with a speed which is less than safe speed of the road then it will slip inwards So option B is correct Also Balancing the forces in the radial direction mv r N sin 0 mv N L N sin 0 mv r i 1 sin 0 1 and 0 Balancing the forces in the vertical direction 90 N cos 0 NA N si

d 5 04 kg m 14 A missile is launched with a velocity less than escape velocity The sum of its kinetic and potential energies is a negative b first zero then negative c zero d positive oming from

7 A projectile is launched from the surface of the earth with a very high speed u at an angle with vertical What is its velocity when it is at the farthest distance from the earth surface Given that the maximum height reached by the projectile is equal to the height reached when it is launched vertically from the earth with a velocity v a u cos 0 2 b u sine 2 c GM V 2R d GM VR GM V3R

a A block attached to a spring the other end of which is fixed to a rigid wall The block moves on a frictionless surface The motion of the block can be described in terms of its distance or displacement from the equilibrium position

11 A block A slides over an another block B which is99 placed over a smooth inclined plane as shown in figure The coefficient of friction between the two blocks A and B is Mass of block B is two times the mass of block A The acceleration of the centre of mass of two blocks is a g sin e g sin e 3 c A d B Fixed g 0 b 9 sin 0 g cos 3 2g sin 0 ug cos 0 3

9 A carrier wave V t 160 sin 27 x 10 t volts is made to vary between V max 200 V and Vmin 120 V by a message signal V t A sin 2 10 t volts The peak voltage A of the modulating signal is anrin TELL 100 N va enri Annala

94 An L C circuit contains a 20 mH inductor and a 50 F capacitor with an initial charge of 10 mC The resistance of the circuit is negligible Let the instant the circuit is closed at t 0 At what time is the energy stored completely AMU Engg 2010 magnetic a t 0 c t 3 14 ms b t 1 57 ms d t 6 28 ms

A block of mass 5 kg is released on rough incline plane Block starts decending with acceleration 6 m s2 the friction force acting on the block is sin 53 YON 1 Zero 3 5 N 4 5 mgsin 3 5 53 F Mg sine Mgcos 53 15x15 4 5 kg 2 10 N 4 20 N 40

1 Observations in the Boy s gas calorimeter experiment on a gaseous fuel are given below Find the G C V and N C V of the fuel Volume of gas burnt STP 0 08 m Mass of cooling water used 29 5 kg Rise in temperature of circulating water 9 1 C Mass of steam condensed 0 04 kg

Gun 0 In a spring gun having spring constant 100 N m a small ball B of mass 100 g is put in its barrel as shown in figure by compressing the spring through 0 05 m There should be a box placed at a distance d on the ground so that the ball falls in it copo 2 m Ba

temperature of a body is degree celsius and degree The graph AB shown in figure is a plot of 100 C Centigrade A B a Slope of line AB is 9 5 b Slope of line AB is 5 9 c Slope of line AB is 1 9 lone of line AB is 3 9 60 32 F 212 F Fahrenheit 320110

A particle of mass 2 kg experience a net force of 8N towards North With respect to a reference frame S acceleration of the particle is 4m s towards 30 North of west Another particle of mass 1 kg experience force of 2 3 towards east What should be magnitude acceleration of the particle with respect to frame S

Two circular rings of same material are of same thickness The diameter of first ring is twice that of second The moment of inertia of first ring as compared to that of second is 1 4 times 3 16 times 2 8 times 4 2 times

10 Which of the following graph shows the induced emf e in the coil with time for the motion shown in figure ex di dt 1 3 e A V L L X X X X x 0 X X X X x L 2 e 4 e

G 5 Direct Indirect speech select the correct option Why did you throw it away said the father to his son I didn t like it said the son a The father asked his son why he threw it away The son replied that he did not like it b The father had asked his son why he threw it away The son replied that he did not like it c The father asked his son that why he threw it away The son answered saying that he had not liked it d The father asks his son why did he throw it away The son replies he did not like it

Which of the following statement is correct 1 A person with myopia can see distant c jects clearly 2 A person with hypermetropia can s nearby objects clearly 3 A person with myopia can see nearby c jects clearly 4 A person with hypermetropia cannot s distant obiects clearly

30 A ball collides with another identical stationary ball with velocity 9m s After the collision the two balls move in directions making an angle of 30 with the initial direction Fig The ratio of the speeds of balls after the collision will be A C E V1 1 V2 V 1 V2 halle 200 B 30 D 30 VL 1 V V V1 1 V2 thrown inair The acceleration of the centre ofmass of the two balls while in air

A ball is projected under gravity with velocity 20 m s at an angle 0 with the horizontal such that horizontal range is equal to the maximum height of projectile The range of projectile is g 10 ms 1 160 m 2 3 2 320 m 3 160 17 m fan 4 320 17

A closed organ pipe of length 1 5m is filled with a gas and it resonates in its fundamental mode with a tuning fork An open organ pipe of same length also resonates with the same tuning fork in its fundamental mode Find speed of sound at 0 C given speed of sound at 30 C is 360m s where the experiment is being performed a 720m s c 360m s b 683 m s d 680m s

L 1 20 sec A standing wave on a string of length L 3 m fixed at both ends is described by y x t 0 01sin x cos 90t where x and y are in meters and t is in seconds The maximum transverse speed of an element on the string located at x 1 6 m is Ov y max 0 6 m s O v y max 0 4 m s O v y max 0 3 m s Ov y max 0 45 m s A standing wave on a string is given by y x t 0 04sin 2x cos 100nt where x and v are in meters and t is in seconds The left end of the string is located at x

Two wires A and B have tension in ratio 8 1 length in ratio 36 35 diameters in ratio 4 1 density in ratio 1 2 find the beat frequency if the note of higher pitch harmonic has frequency of 360 Hz a 5 Hz b 10 Hz c 20 Hz d 350 Hz

0 A gun fires a bullet of mass 80g with a velocity of 50 m s Because of this the gun is pushec back with a velocity of 1 m s What is the mass of the gun 815 1 3 4 kg kg 2 kg 8 4 can t calculate

Question A solid sphere of 2 kg is suspended from a horizontal beam by two supporting wires as shown in fig Tension in each wire is approximately g 10 ms 2 30 O T O 10 N O mg O 5N 30 N 20 N 30

54610 park 1 DOES GOLECCI cxojs Aa Explanation R P cally above his head and to the other end of which is attached weight W 712 N holds one end of a rope that passes over Verified 534 N Find the force with which the man s feet press again A man of weight W 712 N holds one end of a rope that passes over a pulley vertically above his head and to the other end of which is attached a weight Q 534 N Find the force with which the man s feet press against the floor Ans 178