Basic Physics Questions and Answers

A 1 5kg block is initially at rest on a horizontal frictionless surface A horizontal A force F 4 x i is applied on the block Initial position of the block is at x 0 The maximum kinetic energy of the block between x 0 and x 2m is 1 2 331 2 8 67 J 3 5 33 J 4 6 67 J

2 A thin convex lens having focal length 20 cm is cu into two parts 1 mm above the principle axis The lower portion is placed with optical centre at origin and upper portion at 90 0 as shown in the figure A point object is placed at 30 0 Find the magnitude of y coordinates in mm of the image Assuming paraxial ray approximation to remain valid 30 0 1 mm 0 0 30cm 90cm 90 0

3 A capacitor of capacity C 1 F is charged to a potential of 100 V The charging battery is then removed and it is connected to another capacitor of capacity C 2 F One plate of C is earthed as shown in figure The charges on C and C in steady state will be a 50 C 50 C 100 c C n 200 2 C HH C C HH b100 C zero d zero zero

A fluid is flowing through tube At junction it is divided into two cross section with area A 3 and A as shown in the figure The speed of liquid u will be narrow cross section 2A 4 ms 3 ms 1 4 ms1 6 ms 1 18 m s 1 6ms 74 A 3

A feeder with reactance of 0 5 pu has a sending end voltage of 1 8 pu If the reactive power supplied at the receiving end of the feeder is 0 6 pu The approximate voltage drop in the feeder is in pu

1 ug moves in a circle of radius 10 cm under the influence of a magnetic field of induction 0 1 T When the particle is at a point P a uniform electric field is switched on so that the particle starts moving along the tangent with a uniform velocity The electric field is X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 1 0 1 V m 3 10 0 V m X X X X X X Px x X X X 929 2 1 0 V m 4 100 V m 11 4 vyz 100 unpolarized

A certain sample carries a current of 4 A when the potential difference is 2 V and a current of 10 A when the potential difference is 4 V This sample A obeys Ohm s law B has a resistance of 0 52 at 1V C has a resistance of 2 5 D has a resistance of 2 5 E does not have a resistance at 1 V at 2 V

The velocity time graph of a body is shown in the following graph At point C V A B O C D A the force acting on the body is zero B only gravitational force is present e the force opposes the motion of the body D the force is maximum

Water at 20 C is pumped to a large tank from a 40 cm diamater cast iron piping system at a rate of 100 m min Calculate the head loss in the system due to sudden expansion Take the water density and viscosity to be 1000 kg m and 1 3x10 3 kg m s respectively and K to be 1 05

55 A transparent sphere of radius R 2 0 m has mirrored a surface on its right half as shown in figure A light ray travelling in air is incident on the left side of the sphere The incident light ray 1 and exiting light ray 2 are parallel and separated by distance d 2 0 m Then find the refractive index of the material Take sin15 0 25 ANSWER 1 d 2 0 2

Two particles P and P2 move towards origin O along X and Y axis at constant speed 1 and 2 respectively as shown in the figure At t 0 the particle P and P2 are at distances a and b respectively form O Then the instantaneous distances between the two particles is given by the relation P O O O O U U P s a b u u 1 2t aus bu 1 2 8 a b u uz 2t bus auz 8 a b u 1 2t bu auz 2 8 a b u u 1 2 2t bus auz 2

A man swims relative to water with a velocity greater than velocity of water Then A man may cross the river along shortest path man cannot cross the river B C D cannot cross the river without drifting man may cross the river along longest path

The inductance of a closed packed coil of 400 turns is 8 mH A current of 5 mA is passed through it The magnetic flux through each turn of the coil is approximately 1 0 1440 Wb 2 0 20 Wb 3 1 0 4 Wb 4 2 040 Wb

Two charges q and q2 are kept on x axis and electric field at different points on x axis is plotted against x Choose correct statement about nature and magnitude of 9 and 92 424 Question Type Single Correct Type 1 2 3 91 ve 92 ve 1911 1921 91 ve q2 ve l911 1921 91 ve q2 ve 1911 1921

A freezer has coefficient of performance 9 When 200 kcal of work is done on freezer what mass of water at 0 C is converted into ice cubes 0 C Lf 80 cal g 3 6 kg 9 6 kg 22 5 kg 32 5 kg

46 Distance of a planet at perihelion and aphelion from Sun are in the ratio 1 3 Ratio of respective angula speeds at these points about Sun is 1 1 3 2 3 1 3 1 9 4 9 1

Suppose the distance between the Earth and the Moon suddenly doubles without the masses changing How does this affect the force of gravity between them Select one O a It will double O b It will decrease to half of what it is now O c It will quadruple d It will decrease to a quarter of its current value

A bottle is kept on the ground as shown in the figure The bottle can be modeled as having two cylindrical zones The lower zone of the bottle has a cross sectional radius of R 2 and is filled with honey of density 2p The upper zone of the bottle is filled with the water of density p and has a cross sectional radius R The height of the lower zone is H while that of the upper zone is 2H If now the honey and the water parts are mixed together to form a homogenous solution Assume that total volume does not change A The pressure inside the bottle at the base will remain unaltered B The normal reaction on the bottle from the ground will remain unaltered C The pressure inside the bottle at the base will increase by an amount 1 2 pgH D The pressure inside the bottle at the base will decrease by an amount 1 4 pgH R P Honey 2H H

c mv 25 55 A solid sphere of mass 5 kg and radius 1 m after rotating with angular speed wo 40 rad s is placed between two smooth walls on a rough ground Distance between the walls is slightly greater than the diameter of the sphere Coefficient of friction between the sphere and the ground is 0 1 Sphere will stop rotating after time t a 8 b 12 S c 20 d 16

31 A Thick wire in the form of a semicircle of radius r is rotated with a frequency f in a magnetic field What will be the peak value of emf induced 1 Brf 2 Br r f 3 2Br f 4 2B r f

69 A point mass m collides with a disc of mass m and radius R resting on a rough horizontal surface as m shown Its collision is perfectly elastic 777 Find angular velocity of the disc after pure rolling starts 2u 3u a b 3R 2R c 5u 50 2R Disc 2u d 20 5R m R Rough

The potential at a point P due to an electric dipole is 1 8 105 V If P is at a distance of 50 cm apart from the centre O of the dipole and if CP makes an angle 60 with the positive side of the axial line of the dipole what is the moment of the dipole

Two small insulating spheres are attached to silk threads The spheres have equal masses of 40g and have electric charges of q 2 0 C and q 2 0 C The spheres are brought into the initial positions shown in Figure a with a vertical separation of 15 cm between them In figure the upper thread is slowly pulled upward while point B is kept fixed When point A has been raised through a height h the lower sphere suddenly falls as shown in Figure b The height h is closest to A 9 cm B 11 cm D 15cm C 13 cm 91 T 15 cm B a h A 892 b

f earth of nt weight o launch a an altitude S 6 33 If the time period of a satellite Te is different from that of earth s rotation T and the satellite is moving in the direction of earth s rotation show that the time interval between two successive appearances of the satellite overhead is given by E T 1 Is 1 TE What will happen to this time interval if T T Ans T i e the satellite will appear stationary overhead

d 8 A spirit level is placed with its centre at the axis of turntable The bubble will lie a at the centre b at the outer edge c at the inner edge will oscillate about the centre

A ball thrown from ground at an angle 0 37 with speed u 20 m s collides with A vertical wall 18 meter away from the point of projection If the ball rebounds elastically to finally fall at some distance in front of the wall find for this entire motion i Maximum height ii Time of flight iii Distance from the wall where the ball will fall iv Distance from point of projection where the ball will fall

An electron travelling with a speed of 5 x 10 m s passes through an electric field with an acceleration of 10 2 m s How long will it take for electron to double its speed A 0 5 x 109 S 9 C 5 10 s 0 5 x 10 10 S 5 x 10 0 S S B D

sec d 4 sec The driver of a car travelling at 72 km h big rock on the road at a distance of 20 m What can he do suddenly sees avoid a collision AFMC 2007 a Apply brakes c Follow a zig zag path 324 A stone of b Turn sharply d Shut the engine

2a 5a a 1 N c 2 N 63 The angular momentum of a particle about origin is varying as L 4t 8 SI units when it moves along a straight line y x 4 x y in metres The magnitude of force acting on the particle would be DHEADHON b 2 N d 3 N

A straight solenoid has 50 turns per cm in primary coil and 200 turns in the secondary coil The area of cross section of the solenoid is 4 cm Calculate the mutual inductance 1 5 0 H 2 5 0 10 4 H 3 2 5 H

character to the other RE WRITE THE CLIMAX from the point of view of another character Not the Protagonist WRITE THE EPILOGUE CHOOSE 10 12 CHARACTERS from the book and write how they would respond to a controversial statement WRITE A SERIES OF LETTER AND EMAILS between you and a friend talking about what happened in the book PERSONIFY AN OBJECT from the story and have it summarize the story from his perspective WRITE AN INTERVIEW of the

A local train travelling at 72 km hr is brought to rest in 10 seconds by applying the brake How much is the acceleration produced in this case Also how much is distance s covered by the train before coming to rest A a 2 m s s 300 m 2 B a 2 m s s 300 m C a 2 m s s 100 m

The maximum tension which an inextensible string of 0 1 kg m can bear is 10 N The maximum velocity with which it can be rotated is a 10 b 10 c 20 d 15

Five cylindrical wires are made of the same material Their lengths and radii are wire 1 length l radiu wire 2 length 1 4 radius r 2 wire 3 length 1 2 radius r 2 wire 4 length radius r 2 wire 5 length 5l radius 2r Rank the wires according to their resistances least to greatest A 1 2 3 4 5 3 5 4 3 2 1 C 1 and 2 tie then 5 3 4 D 1 3 4 2 5

Two vectors have magnitudes 5 and 3 units but unknown directions the angle between these two vectors is in degree such that resultant vector makes maximum angle with vector of 5 unit Find the value of 10sin Ccircle Concept tangent 8T Ccircle

A block of mass m is tied to a spring of spring constant k natural length I and the other end of spring is fixed at O If the block moves in a circular path on a smooth horizontal surface with constant angular velocity w find the tension in the spring k E

Refer to the arrangement of charges in Fig 1 EP 6 and a Gaussian surface of radius R with Q at the centre Then 5Q R FIGURE 1 EP 6 Gaussian Surface R 2 2Q R a total flux through the surface of the sphere is e 0 b field on the surface of the sphere is Q 4 E R c flux through the surface of sphere due to 5 Q is zero d field on the surface of sphere due to 2 Q is same everywhere

A bullet strikes a plank of thickness 5 cm with a velocity of 1000 m s and emerges out with a velocity of 400 m s the average retardation of the bullet is A 8 4 x 10 m s B C 60 105 m s X D 8 4 x 106 m s 60 x 105 m s

70 A system of uniform cylinders and plates is as shown in figure All the cylinders are identical and there is no slipping at any contact Velocity of lower and upper plate is V and 2V respectively as shown in figure Then the ratio of angular speed of the upper cylinders to lower cylinders is a 3 88 Srbre viss 208 1 b 13 c 1 2v d 1 12

In the figure shown all elements used are ideal For time t 0 S remained closed and S open At t 0 S is opened and S2 is closed If the voltage Vc2 across the capacitor C at t 0 is zero the voltage across the capacitor combination at t 0 will be 3V S C 1F S bcc C 2F

The x and y components of vector are 4m and 6m respectively The x y components of vector B are 10m and 9m respectively Find the length of B and angle that B makes with the x axis OTIONS

ABC is an isosceles triangle right angled A Forces of magnitude2 2 5 and 6N act along BC CA AB respectively The magnitude of their resultant force in N is 90 x and y are axes F is a vector as shown in the figure The ratio of x and y component of vector F is

d gh 23 Two identical balls A and B are released from the positions shown in figure They collide elastically on horizontal portion MN The ratio of heights attained by A and B after collision will be neglect friction boye a 1 4 4h 45 b 2 1 M 2 03 1902 s to lis c 413 N B 60 h d 2 5

a fixed 86 A solid ball is released from rest down inclines of various inclination angles but through vertical height h The coefficient of static and kinetic friction are both equal to u Which of the following graphs best represents the total kinetic energy K of the ball at the bottom of the incline as a function of the angle 0 of the incline KI a c 0 0 0 KI 0 0 0 90 90 b d K 0 0 0 KI 0 0 0 90 90

46 Water with refractive index 3 cm deep Oil of refractive index making a convex surface of radius of curvature R 6 cm as shown Consider oil to act as a thin lens An object S is placed 24 cm above water surface The location of its image is at x cm above the bottom of the tank Then x is in a tank is 18 7 4 lies on water R 6cm S u 1 0 ju 7 4 4 3

23 A sudden drop in the mercury level by 10 mm or more is a sign 0 1 Storm 2 Flood

In the electrolysis of a CuSO4 aqueous solution how many grams of Cu are plated out on the cathode in the time that it takes to liberate 5 6 litre of O g measured at STP at the anode 1 31 75 2 14 2 3 4 32 4 63 5

6 17 In a certain region of space gravitational field is given by 1 K r Taking the reference point to be at r r with V V find the potential at position r

Example 11 26 The coefficient of restitution between a snooker ball and the side cushion is If the ball hits the cushion and then rebounds at right angles to its original direction show that the angles made with the side cushion by the direction of motion before and after impact are 60 and 30 respectively the side cushion

1 In the circuit given below the reading of the voltmeter V will be 1 0 2 100 V 3 200 V 4 300 V V wwww 150 V 150 V 60000005 HH 300 V 50 Hz