Basic Physics Questions and Answers

106 A point charge Q is located just above the centre of the flat face of hemisphere as shown in figure The electric flux through the flat face and curved face of hemisphere are respectively 1 80 80 Q Q EO EO 2 04x 3 d R

A and B are two identical spherical charged bodies which repel each other with force F kept at a finite distance A third uncharged sphere of the same size is brought in contact with sphere of the same size is brought in contact with sphere B and removed It is then kept at mid point of A and B Find the magnitude of force on C F a b 2 c F F 8 d Zero

If Q is the charge on the capacitor and E is the magnitude of electric field between the plates and F is force on each plate of a parallel plate capacitor then a F QE Q A O c F b F 2A Q d F 2A u

2 1 A pebble is thrown vertically upwards from bridge with an initial velocity of 4 9 m s It strikes the water after 2 s If acceleration due to gravity is 9 8 m s The height of the bridge and velocity with which the pebble strike the water will respectively be 1 4 9 m 1 47 m s 2 9 8 m 14 7 m s 4 1 47 m 4 9 m s 3 49 m 1 47 m s

Our use of trigonometry the study of right triangles can be distilled down to the definitions of the three basic trigonometric functions When you know the length of two sides of a right triangle or the length of one side and a non right angle you can solve for all the angles and sides of the triangle if you can use the definitions of the sine cosine and tangent you ll be fine in this course 8 6 m hypotenuse 90 5 m 86 m opposite adjacent adjacent Of course if you need to solve for the angles themselves you can use the inverse trigonometric functions sin 9 05 m opposite hypotemuse opposite cos sin cose tan adjacent hypotenuse opposite hypotenuse tan You ll want a calculator to solve these if you don t have one use this one from desmos adjacent hypotenuse Question If the known non right angle is 35 degrees and the hypotenuse is 15m how tall in meters is the opposite side opposite adjacent

The blades of a windmill sweep out a circle of area A a If the wind flows at a velocity v perpendicular to the circle what is the mass of the air passing through it in time t b What is the kinetic energy of the air c Assume that the windmill converts 25 of the wind s energy into electrical energy and that A 30 m v 36 km h and the density of air is 1 2 kg m What is the electrical power produced C

A highly conducting cylindrical vessel placed on elevated small supports contains an ideal gas under a piston of mass m Area of the base of the cylinder is A The piston is in equilibrium in the mid of the cylinder Friction force between the cylinder and the piston can be ignored Total mass of the cylinder and the gas is M The atmospheric pressure is Po Now the piston is slowly pulled upwards find the maximum value of M such that the cylinder can be lifted off the supports A PA mg g BY PA mg 2g C 2p A mg 2g

A charged particle of mass 10 g is suspended through a silk thread of length 40 cm in a horizontal electric field 4 of 40 x 10 N C If the particle stays at a distance of 24 cm from the wall in equilibrium find the charge on the particle

9 If a crown glass prism of refracting angle 10 have refractive indices for red and violet rays 1 514 and 1 523 respectively then dispersion caused by a crown glass prism is 1 0 09 2 0 10 3 0 07 4 0 08

A particle of mass 40 g and carrying a charge 5x10C is moving directly towards fixed positive point charge of magnitude 10 C When it is at a distance of 10 cm from the fixed point charge it has a velocity of 50 cm s At what distance from the fixed point charge will the particle come momentarily to rest Is the acceleration constant during motion veloc partic mom mu Ar 1

Question 8 1 point Our use of trigonometry the study of right triangles can be distilled down to the definitions of the three basic trigonometric functions When you know the length of two sides of a right triangle or the length of one side and a non right angle you can solve for all the angles and sides of the triangle If you can use the definitions of the sine cosine and tangent you ll be fine in this course 90 degrees hypotenuse 180 degrees 45 degrees 0 sin 48 degrees adjacent tan 0 opposite adjacent Of course if you need to solve for the angies themselves you can use the inverse trigonometric functions opposite opposite hypotenuse sine cose opposite hypotenuse adjacent hypotenuse You ll want a calculator to solve these if you don t have one use this one from desmos Question If the side adjacent to an angle is 22 m and the hypotenuse is 33 m what is the angle adjacent hypotenuse tan opposite adjacent

16 A flare fired from the bottom of a gorge is visible only when the flare is above the rim If it is fired with an initial velocity of 80 ft sec and the gorge is 96 ft deep during what interval can t flare be seen h 16t2 vot ho A 2 t 3 B 6 t 7 C 0 t 2 D 4 t 5

the Find the speed of sound in a mixture of 1 mole of helium and 2 moles of oxygen at 27 C If temperature is raised by 1K from 300K find the percentage change in the speed of sound in the gaseous mixture Take R 8 31Jmole K

A block of mass m is suspended with spring pulley system as shown in figure Find time period of oscillations Spring constant of each spring is k springs and pulleys are light Compare time period with cm 2 Find c X eeeeee eeee Jeee m

For a spherical capacitor shown at which points the electric field is non zero Do X OP Q P R R R

1 2 Design completely a flat belt drive mounted on an electric motor running at 730 rpm The transmitted power is 12 kW having velocity ratio as 4 Considering the position of belt as horizontal and there is considerable variation in load Iterative nature of design improves the design Comment and justify this statement by

mis 10 es to the on it in in it will 39 A electron accelerated by a potential difference V has de broglie wavelength If electron is accelerated by a potential difference 9 V its de broglie Ovelength will be 1 3 3 2 4X 4 9 40 When a red light of wavelength 6500 A is incident

Q6 A point charge of 2 C is placed at the centre of a spherical Gaussian surface How will the electric flux change if a Sphere is replaced by a cuboid of same volume b Another charge of 5 C is placed near but outside the original sphere c Second charge is now placed inside the original sphere d The charge 2 C is replaced by a electric dipole consisting of 10 C separated by 5cm 2

Two beads A and B move along a fixed semicircular wire frame as shown in figure The beads are connected by an inelastic string which always remains tight At an instant the speed of A is u ZBAC 45 and ZBOC 75 where O is the centre of the semicircular arc The speed of bead B at that instant is A 2 u B u C D U 25 u C O centre Alu D

A particle describes a horizontal circle on the smooth inner surface of a conical funnel as shown in figure If the height of plane of circle is 39 2 cm above vertex then speed of particle is g 9 8 m s Vertex 1 96 m s 1 0 98 m s 1 2 45 m s 1 39 2 cm 3 92 m s 1

Resistivity of a material of wire is 3 x 10 6 2 and resistance of a particular thickness and length wire is 2 2 If the diameter of the wire gets doub then the resistivity will be 1 1 1 x 10 2 2 m 3 2 x 10 6 22 m 0 Two condut 2 1 5 10 3 2 m 4 3 10 6 22 m

Two concentric rings of radii r and 2r are placed with centre at origin Two charges q each are fixed at the diametrically opposite points of the rings as shown in figure Smaller ring is now rotated by an angle 90 about Z axis then it is again rotated by 90 about Y axis Find the work done by electrostatic forces in each step If finally larger ring is rotated by 90 about X axis find the total work required to perform all three steps 9 9 9

Assume that a tunnel is dug across the Earth radius R passing through its centre Find the time a particle takes to reach centre of Earth if it is projected into the tunnel from surface of Earth with speed needed for it to escape the gravitational field of Earth

a What is the mean life of a burst of T mesons travelling with v 0 73c if the proper mean fe time is 2 3x10 8 sec b What is the distance travelled at v 0 73c during one mean life c What distance will be travelled without relativistic effect

gentle heat 5 Orthophosphoric acid 220 C What is are correct about X a It is a tetrabasic acid b It contains one P O P bond c It is a dibasic acid d On hydrolysis it produces metaphosphor X

The equivalent capacitance between point A and Bas shown in the figure is Co is capacitance of each capacitors in air A 4KCo O KO 300 4 Co K 3K B

A parallel plate air capacitor is charged to a potential differenc V After disconnecting from battery the plates of capacitor is pushed gently by an insulating handle to decrease the separation between them As a result the charge on the plate O Decreases O Increases O Becomes zero O Remains same

A body moving radially away from a planet of mass M when at distance r from planet explodes in such a way that two of its many fragments move in mutually perpendicular circular orbits around the planet What will be i Then velocity in circular orbits ii Maximum distance between the two fragments before collision and iii Magnitude of their relative velocity just before they collide

Two point like objects each with mass m are connected by a massless rope of length The objects are suspended vertically near the surface of Earth so that one object is hanging below the other Then the objects are released Show that the tension in the rope is T where M is the mass of the Earth and R is its radius R Find the potential eno ass when they are GMml R3

3 A Vo kloge 5 D V klog GM 28 Suppose a smooth tunnel is dug along a straight line joining two points on the surface of the Earth and a particle is dropped from rest at its one end Assume that mass of Earth is uniformly distributed over its volume Then 1 A The particle will emerge from the other end with velocity radius respectively B The particle will come to rest at centre of the tunnel because at this position particle is closest to Earth centre C Potential energy of the particle will be equal to zero at centre of tunnel if it is along tunnel s diameter D Acceleration of the particle will be proportional to its distance from midpoint of the tunnel particle of mass m is transferred from the centr where M and R are Earth s mass and

7 The reading of the ammeter in the given figure will be 1 3 13 T JEF Courrions 413 402 www A 622 4V fi 60 ww A 602 www 2 3 D 4 1 A

4 A nucleus with atomic number 92 emits th following in a sequence a a B B a a a a B B a B B a Th atomic number of the resulting nucleus is 1 76 2 82 3 78 4 74 5 If an axis is passing through the centre of a spher

0 0 Water flows steadily through a horizontal pipe variable cross section If the pressure of water is at a point where flow speed is v the pressu at another point where the flow speed is 2 p density of water 1 p pv 3 p 3pv 2 p 4 3pv 2 py 2 1 The refractive indices of violet and red light are 1 5 4 p

31 The refractive indices of violet and red light are 1 54 and 1 52 respectively If the angle of prism is 10 then the angular dispersion is 1 0 02 3 3 06 2 0 2 4 30 6

1 2 kg 3 16 kg 2 8 kg 4 4 kg 23 A carnot engine has efficiency Efficiency becomes 3 when temperature of sink is decreased by 50 K What was the temperature of the sink 24 1 375 K 3 300 K The pressure P versus 2 325 K 4 350 K density a of given

A charge q moving with velocity voi enters a region of magnetic field B and electric field E 1 If E Bovo then motion of charge particle will be Uniform circular motion Helical motion with uniform pitch Helical path with non uniform pitch Uniformly accelerated motion along straight line

2 small balls having the same mass charge located on the same vertical at heights h h are thrown in the same direction along the horizontal at the same velocity v The 1st ball touches the ground at a distance from the initial vertical At what height will the 2nd ball be at this instant The air drag the charges induced should be neglected

7 67 68 com iv Water flows through a figure 7 62 If the difference of heights of water column in the vertical tubes is 2 cm and the areas of cross section at A and B are 4 cm and 2 cm respectively find the rate of flow of water across any section Take g 10 m s B 2cm Figure 7 62 A

In the circuit shown in figure charge on C is 20 C The potential difference between point A and Bis C 2 F A C3 3 F HH C 2 F O 10 V 20 V 5 V 6 25 V B

Under static condition electric field inside a spherical conductor is o is surface charge density 280 o w 20 0

A spaceship moving away from the earth with velocity 0 5c fires a rocket whose velocity relative o the space is 0 5c a away from the earth b towards the earth Calculate thr velocity of the rocket as bserved from the earth in two cases Kanpur 1988 Delhi 94 1 1 Ja its 11

viii For the system shown in the figure 7 39 the cylinder on the left at L has a mass of 600 kg and a cross sectional area of 800 cm The piston on the right at S has cross sectional area 25 cm and negligible weight If the apparatus is filled with oil p 0 75 gm cm Find the force F required to hold the system in equilibrium Take g 10 m s 37 5 NI 600kg L Figure 7 39 8m 7 6 TH W 7 0 O a

A metre long tube open at one end with a movable piston at the other end shows resonance with a fixed frequency source a tuning fork of frequency 340Hz when the tube length is 25 5cm or 79 3cm Estimate the speed of sound in air at the temperature of the experiment The edge effects amy be neglected

The capacitance of network as shown in the figure between point A and Bis A 20 F 20 F 10 uF HH 5 F HH O 10 F 20 F B

19 If a conductor has a potential V 0 1 point and there are no charges anywhere else outside then O O O a there must be charges on the surface or in side itself b there cannot be any charge in the body of the conductor c there must be charges only on the surface O d both a and b are correct

Two identical circular loops of metal wire are lying on table without touching each other Loop A carries a current which increases with time In response to loop A the loop B Remains stationary Is attracted by loop A Is repelled by loop A

A loop of irregular shape carrying current is located in an external magnetic field as shown in the figure If wire of loop is flexible the wire reshapes itself into 3 B An elliptical shape Circular shape Rectangular shape Equilateral triangle

vii A closed tube in the form of an equilateral triangle of side contains equal volumes of three liquids which do not mix and is placed vertically with its lowest side horizontal Find the value ofx in the figure 7 38 if the densities of liquids are in arithmetic progression x 1 3 B D A Figure 7 38 F E X C

7 A 300 m long train is moving to north at a speed of 10 m s A bird flying towards south with a speed of 5 m s crosses the train The time taken by the bird to cross the train would be 1 30 s 3 10 s moves along 2 20 s 4 15 s snood of the

In a thermodynamic process helium gas obeys the T law constant The heat given to the gas P when temperature of 2 moles of gas is raised from T to 2 Tis 1 8 RT 2 4 RT 3 16 RT 4 Zero If A 31 47 and 871 24k then the vector