Basic Physics Questions and Answers

A point object is kept in front of a plane mirror The plane mirror doing SHM of amplitude 2 cm The plane mirror moves along x axis which is normal to the mirror The amplitude of the mirror is such that the object is always in front of mirror The amplitude of SHM of the image is a 0 c 4 cm b 2 cm d 1 cm

Question 20 A sound source is located somewhere along the x axis Experiment shows that the same wave front simultaneously reaches listeners at x 10 m and x 4 0 m A third listener is positioned along the positive y axis What is his y coordinate in m if the same wave front reaches at him at the same instant it does the first two listeners A 40

A coil of resistance 60 and inductance 318 4 mH is connected in parallel with a 15 F capacitor across a 200 V 50 Hz supply Calculate a the current in the coil b the current in the capacitor c the supply current and its phase angle d the circuit impedance e the power consumed f the apparent power and g the reactive power Sketch the phasor diagram

Question No 110 Fill in the Blank Options The frictional force acting on the block is in Newton 6 kg 7N Max Mark s 03 A 03 n 10 m h

Two equal negative charges q are fixed at points 0 a and 0 a on y axis A positive charge Q is released from rest at the point 2a 0 on the x axis The charge Q will 1 Execute simple harmonic motion 2 Move to the origin and remains at rest 3 Move to infinity 4 Execute oscillatory but not simple harmonic 9

Problem 9 7 12 A string of length L that supports waves at velocity v is displaced at t 0 to have a triangular profile symmetric about its midpoint where the displacement is h Find the displacement at all future times First write down a function that describes the initial displacement

70 A body released from the top of a smooth inclined plane and reaches the bottom of the plane in 4 sec The time taken by the body to cover the first half of the inclined plane is 1 2 sec 2 2 2 sec 3 3 2 sec 4 5 sec 70 Rch odlich von fact and 4 seca 1 2 sec 2 2 2 sec 3 3 2 sec 4 5 sec

Aug 31 2015 Suppose the force Ft in the cord hanging from the wheel is given by the relation Ft St 0 2t 2 newtons where t is in seconds If the wheel starts from res what is the linear speed of a point on its rim 8 s later The Ft force is perpendicular to the wheel s 4 kg radius 33 cm The answer in the Book is 10 m s Can anyone explain HOW Last edited Aug 31

L m 1 4 1 2 1 0 0 8 0 6 0 4 0 2 0 0 0 W 3 6 t s Astronauts in space cannot weigh themselves by standing on a bathroom scale Instead they determine their mass by oscillating on a large spring Suppose an astronaut attaches one end of a large spring to her belt and the other end to a hook on the wall of the space capsule A fellow astronaut then pulls her away from the wall and releases her The spring s length as a function of time is shown in the figure Figure 1 the spring constant is 250m Nlm What is her speed

A B C D K for this reaction is 10 If 1 2 3 4 mole litre of A B C and D respectively are pre in a container at 25 C the direction of reaction will be 1 From left to right 3 Reaction is at equilibrium 2 From right to left 4 Unpredictable

Water stands at a height H in a tall cylinder Two holes A and B are made on the sides of the cylinder If hole A is at a height habove the ground what is the height of hole B above the ground so that the two streams of water emerging from holes A and B strike the ground at the same point 1 2h 2 H 2 3 H h 4 H h 2

A 30 2 resistor is connected in parallel with a pure inductance of 3 mH across a 110 V 2 kHz supply Calculate a the current in each branch b the circuit current c the circuit phase angle d the circuit impedance e the power consumed and f the circuit power factor

In which of the following case s is the power delivered by a given progressive sinusoidal wave in the string is doubled The wave amplitude is doubled keeping the frequency the same The wave frequency is cut in half keeping the amplitude the same The string is made four time as taut keeping its linear density the same The diameter of the string is doubled keeping the tension the same

75 In sports meet the timing of a 200 m straight dash is recorded at the finish point by starting an accurate stop watch on hearing the sound of starting gun fired at the starting point The time recorded will be more accurate a in winter b in summer c in all seasons d none of these

7 For shown situation the acceleration of block is represented by Here t is time in second g 10ms 2 A 0 C L 10 20 tari 0 2 L S Jan 10 1 SEEDS MEDNIE IN 04 03 10kg B I HD F 2 AL02 MIAMI 10 1201 D None of these JURSO

2 A source of sound produces waves of wavelength 60 cm when it is stationary If the speed of sound in air is 320 m s and source moves with speed 20 m s the wavelength of sound in the forward direction will be nearest to a 56 cm c 64 cm b 60 cm d 68 cm S

Q 6 In an industry an engineer is designing a de shunt machine working as a motor It is containing an armature res of 0 060 and shunt resistance of 2200 in dc shunt motor When he gives supply of 220V dc then motor runs at a sp 1000rpm Initially dc shunt motor works at no load and motor is taking 6A current Now when he places a motor takes 31A current Then evaluate a Speed of motor at which motor is running at full load b Speed of motor at which motor is running at no load

The graph below represents the history graph of travelling wave at x 2 m Wave is traveling in positive x direction with velocity 2 m s Choose the snapshot graph at t 4 sec displacement m 1 5 05 0 5 at x 2 m K

Each the three graphs represents acceleration versus time for an object that already has a positive velocity at time 1 Which graphs show an object whose speed is increasing for the entire time interval between 1 and 12 a a 1 a graph I only c graphs I and III only TI 1 1 a 1 b graphs I and II only d graphs I II and III 1

7 A ball of mass m 1 kg is released on an smooth inclined plane of length and inclination 0 It hits a rigid board elastically which is fixed at a distance l from the bottom Impulse in Sl unit imparted by board on the ball is 4 8 Given lg sin0 in Sl unit 3 114 4 E

9 A chain or rope of indefinite length passes freely over pulleys at heights y and 2 above the plane surface of Earth with a horizontal distance x2 x between them If the chain or rope has a uniform linear mass density show that the problem of finding the curve assumed between the pulleys is identical with that of the problem of mini mum surface of revolution

A stone is projected from ground with a velocity of 50 m s at an angle of 30 from horizontal It crosses a wall after 3 seconds How far beyond the wall stone will strike the ground 1 125 3m 2 50 2m 3 50m 4 70 m

Question NO Multiple Choice Select 1 out of 4 options for the question below Find the frictional force on the block as shown in figure If block is pushed with 15 N force on a rough surface g 10 m s F 15 N Options m 15kg O 15 N O 30 N 35 N p 02

A solid ball 3 cm in diameter is submerged in a lake to a depth where the pressure is 10 kgfir What is change in volume of the ball if bulk modulus of the material of the ball is 10 dyne cm 1 0 15 cm 2 1 5 cm 3 1 386 cm 4 0 1386 cm

Question No 49 4 Multiple Choice Select 1 out of 4 options for the question below Find acceleration of the block in the given diagram Options 100 kg O2 5 m s 500 N Max Mark s 04 60 u 0

The system of three particles has the indicated particle masses velocities and external forces If r represents the location of the center of mass determine r d r dt d r dt2 T Ho and d Ho dt for this two dimensional system 2 3 kg 0 78 m 1 8 m s 1 02 m 1 4 m s 4 4 kg 10 9 N 1 0 kg stationary

Time intervals measured by a clock give the following readings 1 25 s 1 24 s 1 27 s 1 21 s and 1 28 s What is the percentage relative error of the observations NEET 2020 Phase 2 1 1 6 2 2 3 4 4 16

ve a vertical cylindrical magnetic rod as shown in Fig 5E 69 The axis of symmetry of the ring is the same as that of the rod The cylindrically symmetrical magnetic field around the ring can be described approximately in terms of the vertical and radial components of the magnetic field vector as B B 1 02 and B Bo r where Bo a and are constants and z andr are the vertical and radial position coordinates respectively B Properties of the ring Mass Radius B Fig 5E 69 Initially the ring has no current flowing in it When released it starts to move downwards with its axis still vertical From the data below determine how the ring moves subsequently What current flows in the ring Data m 50 mg To 0 5 cm Inductance L 1 3 108 H Initial coordinates of the centre of the ring z 0 r 0 motic fold constants

Paragraph for Question 20 21 An object of mass M is gently placed on a horizontal conveyor belt which is moving with uniform velocity v as shown in the figure The coefficient of static friction is u the coefficient of kinetic friction is and the acceleration of gravity is g Initially the object slips for a while but finally moves without slipping together with the belt How far the conveyor belt moves while the object is slipping V 2 8 A 0 g B A MV B Mv C Work done on the object by friction force relative to the reference frame moving with the conveyer belt is 2 Msg D C Mv 2 g D zero

b A block P of weight 50 N is kept on a plane and now pulled so that the extension in the spring is 10 cm The stiffness of the spring is 4 N cm and the coefficient of friction between the block and the plane is 0 3 Find i the velocity of the block as the spring returns to its undeformed state and ii the maximum compression in the spring

There is a column University Students Number USN in a college database that is used to save the unique number assigned to all students of first year engineering You cannot save the names of some students along with mobile numbers of other students in the column This column is applicable to save only USN of all students This scenario is an example of which rule of the first normal form

A thin uniform rod has moment of inertia I about an axis parallel to its length at a certain distance If on heating its length increases by 2 then moment of inertia of rod will change by A 0 C 2 B 1 D 4

2 Consider a rigid body which consist of hemispherical shell of radius R and uniform cylindrical shell of height L and radius R material of hemispherical shell and cylindrical shell are same Find maximum value of L so that complete rigid body remains in stable equilibrium in the position shown neglect friction 3R 1 3 WHO N R L 2 R 4 4R upplied on a uniform circular

A box has square base ABCD each of length 1m in the horizontal plane moving horizontally with speed 1 m s as shown A ball is to be given a velocity from C to reach B in 2 seconds The velocity of ball in earth frame is A 1 m s B 2 m s B D 15 1m s C 3 m s D 2 m s

I have N distinguishable and identical particles There are two energy levels 0 and 0 The energy level has degeneracy 2 and the lower level is non degenerate The total energy of the system is E Find the occupation numbers n using microcanonical ensemble in terms of temperature The n is quanta of energy for the upper level and n is the quanta of energy for the lower level e B 1 e BE 2e Be 1 2e Be e A 1 e Be 2e Be 1 2e Be a N b N c N d N

When a metal wire elongates by 1 after hanging a load Mg on it the gravitational potential energy of mass M decreases by Mgl This energy appears 1 as elastic potential energy completely 2 as thermal energy completely 3 half as elastic potential energy and half as thermal energy 4 of the load completely

Pressure is increased by 1 atm and temperature also increased by 1 C for a gas initially at STP then velocity of sound in gas 2 1 Increases by 61 m sec approx Decreases by 61 m sec approx 3 Increases by 61 cm sec approx 4 Decreases by 61 cm sec approx

A ball is dropped from roof of a building of heigh h and at the same instant another ball is projectec upward with speed v 1 Both balls wire always meet on the way at time t V Vo g 2 balls will not meet if h 2u g ho 00 vo 1 0 2 90 3 180 3 balls will never meet on the way 4 If balls meet the speed of the balls will same at the time of melting ho 38 What can be the angle between P Q and p Q 2 PQCOSO P Q 4 PQ COSO P Q 2 P Q COSO

When a person walks on a rough surface the net frictional force exerted by the surface on the person is opposite to the direction of his motion When a body is sliding down a rough inclined surface at a constant velocity the net force exerted by the surface on the body is vertical A body resting on a horizontal rough surface is acted on by a horizontal force The frictional force acts on the body only when it just starts sliding Frictional force between the surfaces of two

1 The loudness of sound coming from a point source at a distance of 1 m from the source is 10 bel the loudness of sound at a distance of 10 m from the same source will be 1 10 bel 3 12 bel 2 8 bel 4 None

Point charge 4q q and 4q are kept on the x axis at points x 0 x a and x 2a respectively then 1 Only q is in stable equilibrium 2 None of the charges are in equilibrium 3 All the charges are in unstable equilibrium 4 All the charges are in stable equilibrium

In a water fall the water falls from a height of 100m If the entire K E of water is converted into heat the rise in temperature of water will be 1 0 23 C 1xxx wis At 2 0 46 C migh 3 2 3 C 4 0 023 C 10 2 10000 4300 4 2X103 100 40 of three differer

You have 6 to use as the air gap for a wood panel absorber which is to absorb at 90 Hz What does the surface density of the panel need to be a 0 18 lbs ft2 b 0 31 lbs ft2 c 0 43 lbs ft2 d 0 59 lbs ft2 None of the above

The intensity of a wave of frequency 1 KHz is 10 10 W m If the density of the air is 1 3 kg m and the speed of sound is equal to 330 m sec then pressure amplitude of the wave is approximately 1 3 x 10 5 N m 3 3 x 10 6 N m 2 3 x 10 4 N m 4 3 x 10 3 N m

1 Assertion A Distance is the total path covered during a journey Reason R Displacement is the shortest path covered during a journey 2 Assertion A Momentum depends directly on mass of the object Reason R momentum depends inversely on velocity of the object 3 Assertion A Inertia is independent of mass of the object Reason R Inertia only depends on state of the object 4 Assertion A Scalar quantity has magnitude only Reason R Vector quantities have magnitude as well as direction a Both A and R are true and R is the correct explanation of A b Both A and R are true but R is NOT the correct explanation of A c A is true but R is false A is false and Ris

5 4 When the current through a solenoid increases at a constant rate the induced current in the solenoid A Is a constant and is in the direction of the increasing current in it B Is a constant and is opposite to the direction of the increasing current in it C Increases with time and is in the direction of increasing current in it 01 sa V D Increases with time and is opposite to the direction of the increasing current in it

5 identical balls are at rest on a smooth horizontal table Four balls are given velocity v and the last one is at rest Each collision is perfectly inelastic from the shown instant If total time till last 2 5 al V collision is find a 00000 0 0 0 Orest

2 A man who can swim at the rate of 2 km h in still river crosses a river to a point exactly opposite on the other bank by swimming in a direction of 120 to the flow of river water The velocity of water current in km h is 1 1 3 2 2 4 33w

A satellite in force free space sweeps stationary interplanetary dust at a rate dM dt av Here v is the velocity The acceleration of satellite of mass M is 1 2 av M 3 av M 2 3 av M 4 av 33

irl throws a ball horizontally with velocity u from a height h directly towards a vertical wall at a distance L After colliding with the ground once the ball hits the wall izontally at a point P as shown The height of the point P above the ground is given by UL