Basic Physics Questions and Answers

A person stands on a platform and pulley system as shown in the figure The masses of platform person and pulley are M m and u respectively The rope is massless Let the person pull up on the rope so that he has acceleration a upwards Tension in the rod connecting the pulley to the platform is A M m u g a C 2M 2m u g a M m B M 2m u g a D 2M m 2u g a

The following figure shows the velocity time graph for a body According to this at the point B which of the following is are incorrec The net force on body is zero The net force on body is increasing with time The net force on body is decreasing with time The body is retarding

D 261 m in direction tan A ball is thrown at speed v from horizontal ground At what angle should it be thrown so tha the area under the trajectory is maximum A 15 B 30 C 45 m LE south of east D 60

A rectangular block of size 10cm x 8cm x 5cm is kept in three different positions P Q and R in turn as shown in the figure In each case the shaded area is rigidly fixed and a definite force F is applied tangentially to the opposite face to deform the block The displacement of the upper face will be 10 P R 10 10 Q Same in all the three cases

In the YDSE shown the two slits are covered with thin sheets having thickness t and 2t and refractive index 2 and u Find position y of the central maxima 11 O Zero O 3D 1 2 21 H O XI

John Paul and George are standing in a strawberry field Paul is 14 0 m due west of John George is 25 m from Paul in a direction 37 0 south of east from Paul s location How far is George from John What is the direction of George s location from that of John A 261 m in direction tan B 1381 m in direction tan C 1381 m in direction tan D 261 m in direction tan 5 2 south of east 15 34 19 34 3 5 south of east south of east south of east

Vo 10 2R Vo Yo 3R www At t to potential across capacitor is 2 through capacitor is lo then Read Less C If current

The nucleus Cu half life 12 7h is known to decay by electron capture 61 contribution to total decay rate and decay 39 contribution to total decay rate Partial half lives for electron capture and decay respectively are A 20 8h 32 6h C 61h 39h B 28h 32 6h D 23h 28 4h

50 System of Partices 99 A light rigid rod of length 2 is welded with another rod of mass m and length 2 The light rod is hinged at the free end and the combination is given an angular velocity such that the centre of mass moves with velocity v The Kinetic Energy of rod is www 21 m 2

A wheel turns with a constant angular acceleration of 8 1 rad s 2 If the angular speed of the wheel is 2 rad s at t 0 find the revolutions at t 2 0 seconds Knowing that the initial angular speed is 7 rad s

Two ships A and B at a given instant are 5 km away from each other The ship A is South East of the ship B If the ship B is travelling at 10 km p h due East and the ship A is travelling at 16 km p h due North determine i velocity of the ship A relative to the ship B ii shortest distance between the two ships and iii the time when the two ships are nearest to each other

Block A B of mass 5 kg 4 kg are placed in contact on an inclined plane of angle 0 coefficient of friction between A plane is 0 2 while there is no friction between B and plane The value of 0 when blocks are about to slide is tan 0 n Find n 4 B

Two point charges 9e and e are kept 16 cm apart Where should a third charge q be placed between them so that it is in equilibrium state a 24 cm from 9e b 12 cm from 9e c 24 cm from e from

The electric potential in a certain region of space is given by V 3x 4x where x is in meters V is in volts In this region equipotential surface are O Plane parallel to XY plane O Plane parallel to YZ plane O Concentric cylinder with axis as x axis O Concentric spheres centred at origin

The value of the horizontal component of the earth s magnetic field and angle of dip are 1 8 10 Weber m and 30 respectively at some place The total intensity of earth s magnetic field at that place will be 1 2 08 10 Weber m 2 3 67 10 Weber m 3 3 18 10 Weber m 50 10 Weber m

its ends at x U and x L Its linear density varies O with x as K positive number If the position Xcm of the centre of mass of the rod is plotted against n which of the following graphs best approximates the dependence of Xem on n x c m ven L K 3 x c m L 2 L 2 X c m L I L 2 L 1 1 1 1 I X c m where n can be zero or any I n n

A particle moves in a straight line The acceleration of particle varies with time as a 3t 2t 2 where all quantities are in Si units If initial velocity is 2 m s then velocity at the end of 2 s in m s comes out 3 x k find k

Unpolarized light travels through 2 linear polarizers What minimum angle should the second polarizer be relative to the first polarizer the difference between and so that the final intensity of light is 3 8th of the original value A C 3 4 B D FORN 6 2

A river stream is flowing at 5 km h A man wants to reach point B starting from point A as shown in figure Choose possible values of swimming speed of man in still water to reach directly at point B B J 308 A 3 2 km h 5 km h 2 9 km h 5 km h

Class 12 Physics IIT JEE Mains Ad In Young s double slit experiment 62 fringes are seen in visible region for sodium light of wavelength 5893 If violet light of wavelength 4358 is used in place of sodium light then number of fringes seen will be RPET 1997 a 54 c 74 b 64 d 84

4 identical particles are connected with four massless springes and placed at corners of square as shown in figure Strings 1 and 2 are massless and vertical and whole system is in equilibrium Just after string 1 is cut acceleration of A will be A 2g downward C g upward 1 mom 0000000 me voors 2 B zero D g 2 at 45 with AD oooooo

A gas contains many positive and negative ions initially at rest It is then subjected to E towards ve x axis If a magnetic field is setup along positive z axis then the deflection of positive and negative ions are respectively towards 1 negative y axis 2 negative y axis and negative y axis 3 positive y axis and negative y axis 4 positive y axis and positive y axis

A screw gauge has some zero error but is value is unknown We have two identical rods When the first rod is inserted in the screw the state of the instrument is shown by diagram I When both the rods are inserted together in series then the state is shown by the diagram II What is the zero error of the instrument 1 msd 100 csd 1 mm A 0 16 mm B 0 16 mm C 0 14 mm 12 D 0 14 mm 10

A man is walking with a speed of 3 km h in rain and rain drops appear to fall vertically on the man When he runs at speed of 6 km h rain drops appears to fall at angle of 30 with the vertical then Vertical component of rain velocity has magnitude 3 3 km h Horizontal component of rain velocity has magnitude 3 km h Vertical component of rain velocity has magnitude 4 km h Horizontal component of rain velocity has magnitude 7 km h

14 A dry cell of emf 1 5V and internal resistance 0 1002 is connected across a resistor in series with a very low resistance ammeter When the circuit is switched on the ammeter reading settles to a steady value of 2 0A What is the steady i rate of chemical energy consumption of the cell ii rate of energy dissipation inside the cell iii rate of energy dissipation inside the resistor and iv power output of the source 3 0W 0 40W 2 6W 2 6W

Two cars A and B are moving towards each other on a straight road with velocity 10 m s and 20 m s respectively When they are 150 m apart then car A decelerates with m s 5 and car B decelerates with 1 m s until 3 they stop in order to avoid collision If the distance in m between them when they come to rest is 15 x k then find k

A solid sphere of mass M and radius R having moment of inertia I about its diameter is recast into solid disc of radius r and thickness t The moment of inertia of disc about edge and perpendicular to plane is I then r 1 r 2 r 3 R 15 R 4 R 4 2R r

15 A 24 V battery of internal resistance 4 0 is connected to a variable resistor For what value of the current drawn from the battery is the rate of heat produced in the resistor maximum 3 0A

John wants to lift 800 N box from the ground to keep it into a trolley He fixes one end of a long beam at the weight and applies his whole weight 490 N on the other end after keeping a proper support to the beam to act What is the mechanical advantage of the lever in 2

he amplitude of a particle executing SHM about O is 10cm Then When the K E is 0 64 of its max K E its displacement is 6 cm from O When the displacement is 5cm from O its K E is 0 75 of its max P E Its total energy at any point is equal to its maximum K E Its velocity is half the maximum velocity when its displacement is half the maximum displace

A particle is moving in a circle of radius 3 m with an angular speed 2 radian per second in clockwise direction as given in the diagram The acceleration in m s2 of particle at point Pis 3m f aferad fan 2 fu fitfam 60 X A B C 61 6 3 61 6 3 6 31 61 D 61 6 3 Your Answer

Coulomb s law for the magnitude of the force F between two particles with charges Q and Q separated by a distance d is F Klad 1 where K and 4TCO 08 854 x 10 2 C N m is the permittivity of free space Consider two point charges located on the x axis one charge q 15 5 nC is located at T1 1 680 m the second charge q2 33 0 nC is at the origin r 0 Part A What is Fnet 3 the x component of the net force exerted by these two charges on a third charge q3 48 0 nC placed between 91 and 92 at x3 1 135 m Your answer may be positive or negative depending on the direction of the force Express your answer numerically in newtons to three significant figures View Available Hint s Fnet 3 z V AZO C N

A car starts moving rectilinearly first with acceleration w 5 0 m s the initial velocity is equal to zero then uniformly and finally decelerating at the same rate w comes to a stop The total time of motion equals T 25 s The average velocity during that time is equal to v 72 km h The car moves uniformly for 10 x seconds The value of x is

Two exactly similar wires of steel and copper are stretched by equal forces If the difference in their elongations is 0 5 cm the elongation of each wire is O O Y steel 2 0 x 10 N m Y copper 1 2 x 10 N m 1 0 75cm l 1 25cm l 1 25cm le 0 75cm 1 0 25cm l 0 75cm 0 75cm l 0 25cm

D 128 h Two isotopes P and Q of atomic weight 10 and 20 respectively are mixed in equal amount by weight After 20 days their weight ratio is found to be 1 4 Isotope P has a half life of 10 days The half life of isotope Qis A zero B 5 days 20 days Dinifinite

The focal length of the eyepiece and the objective of an astronomical telescope are 4 cm and 50 cm respectively The length of the telescope for the adjustment in which eye is most strained will be about least distance of distinct vision is 25 cm NCERT Pg 341 1 63 cm 3 53 cm 2 45 cm 4 40 cm distance a in

A circular loop of radius R carries current lo and is parallel to the x y plane A uniform magnetic field is switched on such that tension in the loop becomes To Force exerted by right half of the loop on the left half is 2 10 To 2To

es as to each other and are in mutually shown in figure 4 213 IfI 24 along the y axis and I 34 along negative z axis and AP AB 1cm The magnetic induction B at point P is P 1 A AY Figure 4 213 A 3 10 5T 4 10 5T k X B 3x 10 5T j 4 10 5T k C 4x 10 5T 3 10 5T k B

23 Decimal number 27 is equivalent to Binary number A 10111 B 10101 C 11001 D 11011 2 24 The resultant of two vectors A and B is perpendicular to A and it has magnitude half that of B Th angle between the vector A and B is A 90 B 120 C 140 D 150

Two point charges tq and zq are placed at the vertex B and C of an equilateral tringle ABC of side a obtain the expression for magnitude and direction of resultant electric field at vertex A lue to these two charges 8 00 pm

Angle of dip in a vertical plane P is 30 Angle of dip in other vertical plane Q is 45 Plane P and plane Q are perpendicular The true angle of dip is Question Type Single Correct Type 1 2 3 tan 1 4 tan 1 2 V 3 cot 2 1

Which among the following statement is correct O Natural convection occurs only in gravity free space O Natural convection can occur in space having gravity as well as gravity free space O Forced convection occurs only in space having gravity O Forced convection can occur in gravity free space

Using a displacement time graph depict t he journey of a bike which started the j ourney with an acceleration of 20ms 1 an d then after reaching a velocity of 40 m s 1 continued for a uniform speed for 4 0 seconds before starting deceleration a t the rate of 20ms 1 before reaching fina I stop

Four equal masses M are kept at the corners of a regular pentagon as shown Distance between centroid and any vertex of the pentagon is R If another point mass mo is kept at the centroid of the pentagon then force acting on mo due to four masses is M M mo R M

Two metallic shells of radii R 2R are initially uncharged They are connected to the two terminals of a battery by a long wire of some resistance as shown in the figure If the work done by the battery in this process is 30 find the potential energy of the bigger shell in 0 V

If the mass of Moon is 81 where M is the mass of Earth find the distance of the point where gravitational field due to Earth and Moon cancel each other from the center of the Moon Given that distance between Earth and Moon is 60 R Where R is the radius of Earth O O O 2 R 4 R 6 R

A centrifuge has about a vertical axis as shown in the figure Water inside it has density p a Consider a point A inside the liquid at a distance r from the rotation axis Liquid pressure at this point is P Write the value dP of when the cylinder with all its liquid dr rotates uniformly at an angular speed w b Consider a small disc shaped foreign material inside the centrifuge at point A The area of circular disc is AS and its thickness is Ar It is made of material of density p p The disc is in position so that its circular face is vertical Find the radial acceleration of the disc with respect to the cylinder when angular speed of rotation is O Xsa A Ar

Two simple following equations 45 harmonic motions are represented by the c 17 mode y 40 sin ot y2 10 sin oot c cos wt and If their displacement amplitudes are equal then the value of c in appropriate units is a 13 b 15 d 4 gy of a particle of mass 2 kg in

In the figure shown the point P moves with constant speed of 5 m s and velocity vector always makes an angle of 60 with the line PQ If point Q was initially at a distance of 80 m from P then time taken in s by P to reach Q is 8 xk find value of k Answer 60 506

Choose the wrong statement A The nuclear force becomes weak if the nucleus contains too many protons compared to the numbe of neutrons The nuclear force becomes weak if the nucleus contains too many neutrons compared to th number of protons C Nuclei with atomic number greater than 82 show a tendency to disintegrate The nuclear force becomes very strong if the nucleus contains a large number of nucleons