Basic Physics Questions and Answers

8 A body of mass 2 kg is allowed to slide down along a quadrant circle from the horizontal position In reaching the bottom its velocity is 6m sec The work done in overcoming the friction is 10J The radius of circle is g 10ms

volts given 7 An alternating voltage in V 200 2 sin 100t is connected to 1 HF capacitor of the ammeter and the average power consumed in through an ideal a c ammeter in series The reading the circuit shall be

Consider the following T S diagram for a reversible Carnot engine S J K 200 100 T K 300 600 Which of the following is are correct Work delivered by the engine in one cycle is 30 J CORRECT ANSWER Heat taken from the source in each cycle is 90 kJ In each cycle AS sink is 100 JK 1 Efficiency of cycle is 05

Assertion The resistance of a given mass of copper wire is inversely proportional to the square of length Reason When a copper wire of given mass is stretched to increase it s length its cross sectional area also decreases

Ans 216 J 3 39 A bicyclist of mass 80 kg including the bicycle can coast down a 3 4 hill at a steady speed of 6 kph Pumping hard the cyclist can descend the hill at a speed of 30 kph Using the same power at what speed can the cyclist climb the same hill Assume the force of friction is directly proportional to the speed v Ans 24 kph

period of earth of radius R When taken to a height of R above the earth s surface its time period is T ratio T is 1 T b 2 2 a

a substance remains constant with elevation but its weight varies with elevation What is the weight of a 1 kg mass at an altitude where the local acceleration of gravity is 9 75 m s

3 79 Figure 3 136 shows a rod of length 20 cm pivoted near and end and which is made to rotate in a horizontal plane with a constant angular speed A ball of mass m is suspended by a string also of length 20 cm from the other end of the rod If the angle 0 made by the string with the vertical is 30 find the angular speed of rotation Take g 10 m s 10 m

resistacne between point A and B for 27 following network is each branch of resistance is R www 1 inim R D 33 32 2 R 3 R The potential difference across 8 ohm resistance is 28 48 volt as shown in the figure The

2 6 What is the pressure at the bottom of the 7 5 m tall storage tank of fluid at 25 C shown in Fig 2 15 Assume that the fluid is gasoline with atmospheric pressure 101 kPa on the top surface Repeat the question for the liquid refrigerant R 134a when the top surface pressure is 1 MPa

3 74 A block of mass 5 kg is suspended from the end of a vertical spring which is stretched by 10 cm under the load of the block The block is given a sharp impulse from below so that it acquires an upwards speed of 2 m s How high will it rise Ans 20 cm

The radioactivity of an old sample of a liquid due to tritium half life 12 5 years was found to be or about 3 of that measured in a recently purchased bottle marked 7 year old The sample must ha been prepared about D 300 year A 70 year B 220 year C 420 year

37 Four cells each of emf E and internal resistance r are connected in series across an external resistance R By mistake one of the cells is connected in reverse Then the current in the external circuit is WB JEE 2014 2E d 3r R a 2E 4r R Shibno 3E b 4r R c 3E 3r R f thro batteries of emf E 1V

Q4 Consider the situation shown in the figure The capacitor A has a charge q on it whereas B is uncharged The charge appearing on the capacitor B a long time after the switch is closed is 2001 D 9 A 0 AF S B D

3 53 A point moves along a circle with a velocity v kt where k 0 5 m s Find the total acceleration of the point at the moment when it covered the nth fraction of the circle after the beginning of motion n being 0 1 Ans 0 8 m s

If the parrot starts flying upwards with an acceleration in an air tight cage then the boy will feel the weight of the cage Question Type Single Correct Type 1 unchanged 2 3 lesser than before more than before

nitially both springs are relaxed and block of mass m is attached to springs as shown n the diagram spring constant K and K Now answer the following questions 1 Maximum elongation in spring will be A mg K K C 2mg K K B mg 2 K K D 3mg 2 K K 8880000 8000000 H

Consider a system comprising of a magnet and a charged particle Would there be any force acting on the particle if i the magnet and the particle are both at rest ii both of them move with the same velocity iii the particle is at rest but the magnet is in motion iv the magnet is at rest but the particle is in motion

In the circuit shown in the figure four identical resistors labeled A to D are connected to a battery as show 1 and S2 are switches Which of the following actions would result in the GREATEST amount of current through resistor A A W O closing S1 only O closing both switches S B ww C ww D WW

6 A student connects 10 dry cells each of emf E and internal resistance in series But by mistake 1 cell gets wrongly connected The net emf and the net internal resistance of the combination will be O 8E 10r O 8E 8r O 10E 10r O 8E r 10

Assertion The current density is a vector quantity Reason Current density has magnitude current per unit area and is directed along the direction of current

If Enthalpy of combustions of C graphite and CO g are x and mol respectively then the enthalpy of formation in kJ mol 1 of CO g will be O x1 x2 O X1 X2 x1 x2 O x1 x2 2

SolveLancer Test Choose the incorrect statement among the following regarding observations from the alpha particle scattering experiment SolveLancer Test a Most of the alpha particles passed through the foil without any deviation b Most of the space is occupied as about 99 86 of alpha particles deviates c d About 0 14 of the incident alpha particles scattered by more than 1 Deflection of more than 90 was observed in about 0 0125 of the incident alpha particles

A ball is allowed to fall freely from a height of 3 m on to a fixed plate The successive rebound heights are h h h3 If the distance covered by the ball before coming to rest is x metres the value of x is Given that the coefficient of restitution is 0 5

A square surface with side length 5 50 cm is in the xy plane at z 0 Calculate the magnitude of the flux throug this surface produced by a magnetic field B 10 310T 0 450T J 0 610 T k O 0 00672 Wb O 0 00456 Wb 0 00336 Wb 0 000578 wb

Calculate the rise in temperature in the Earth during accretion due to impacting by planetesimals of mass 10 5 kg with a velocity of 104 ms assuming that the heat generated by the impact spreads rapidly and uniformly throughout the Earth Assume specific heat of Earth material to be 750 JKg K 1 and mass of Earth as 6x1024 Kg

II A vire of resistance m is to form a complete circle of radius 10cm The resistance between it s two diagrammatically opposite points A and B as shown in the figure is Fig iii 30 6 JQ 6Q 0 6 JO Fig iii A O B 1 point

15 kg of gas is contained in a cylinder at a pressure of 2 x 107 N m quantity of gas that should be taken out of the cylinder while keeping temperature constant such that the pressure becomes 2 x 106 N m is O 10 kg O 12 kg O 13 5 kg O 15 kg

SolveLancer Test 2 moles of gas is held at constant volume The temperature of the gas is changed from 300 K to 400 K The change in internal is found to be 100 J Find the total heat capacity of the gas as constant volume SolveLancer Test a 5 JK 1 b 3 JK c 1 JK 1 d 2 JK

SolveLancer Test In the following P V diagram an ideal gas is compressed to half of its original volume of 2 m in a quasi static process for which P aV with a 10 atm m How much work is done on the compressing gas SolveLancer Test P atm a 2 52 x 106 J b 5 52 x 106 J c 1 52 x 106 J d 3 52 x 106 J 1 2 V m

2 Assume that each atom of copper contributes 1 free electron The current flowing through a copper wire of 1mm diameter is 1 1 A the drift velocity of the electrons will be density of Cu 9x10 3 kg m 3 atomic weight of Cu 63 Avogadro number 6 022 x 10 23 kg atom 0 3 mm s 0 5 mm s 0 1 mm s 0 2 mm s 1 pc

An observer located close to the mirror and 3R 4 below the axis is looking at the image of a distant point P made by a circular mirror of radius R If the central part of radius R 2 is removed from the mirror then the ratio of intensity received by the eye before and after the removal of central part will be A 1 1 P AN B 4 1 Op R C 16 1 R 2 D 2 1

Alpha particles charge e mass 3 34 x 1027 kg e 1 60 x 10 19 C are accelerated in a cyclotron to a fina orbit radius of 0 90 m The magnetic field in the cyclotron is 0 30 T The period of the circular motion of the alpha particles is closest to 0 65 pus 0 44 ps O 1 3 pr O 0 87

Determine the resultant of the forces originating at point 3 3 and passing through the point indicated 126 N through 8 6 183 N through 2 5 and 269 through 6 3 Ans R 262 53 N 0 21 37 ABCD is a co as shown in Figure 1 side being 20 cm and E is the middle point

The region between two concentric spheres of radii A a and 2a has volume charge density p r where A is constant and r is distance from the centre A point charge Q is placed at the centre If the potential in the region a r 2a varies linearly then value of A is 1 6na 2Q a 3 2 2Q 3 a Q 2 a

Which of the equations is valid for the circuit below a 2 1 21 0 b 2 21 21 41 0 c 2 1 4 21 0 d 1 4 21 6 0 e 2 1 31 6 0 1 2V ww 192 10 www 202 4 V 6 V wwwww 352

1 Two cars A and B are moving in same direction such that A is behind B with same speed v and are blowing horn of frequency f If a cyclist is moving between two cars from B to A with speed vo then the beat frequency observed by cyclist is v is velocity of sound in air 1 2vf 3 Vo V1 v vi vo V12vf 2 2 2 vf Vo V1 v v V 4 zero

Assertion During radioactive disintegration an a particle and B particle do not emit simultaneously from any nucleus Reason An a particle emits from a nucleus when the N Z ratio is less than the stability range where N number of neutrons and Z number of protons in a nucleus 1 A 2 B C 4 D

In case of circular motion of a body if tangential force also acts on the body in addition to centripetal force then work done 1 by tangential force is zero and by centripetal force is not zero 2 by centripetal force is zero and by tangential force is not zero 3 by both the forces is positive 4 by both the force is zero 6

Example 34 A bag contains n white and n red balls Paris of balls are drawn without replacement until the bag is empty Show that the probability that each pair consists of one white and one red ball is 24

A uniform straight rod of mass M and length L Is having small rollers of negligible mass at its ends Rod Is moving on smooth horizontal surface with constant speed vo in gravity free space Find the normal reaction at the rear roller from horizontal surface just after front roller crosses P P is starting point of smooth vertical cylindrical surface of radius as shown in figure L

Electric flux equation cos is 90 degree mean electric field and area both parallel and if cos 0 or 180 electric field and area both perpendicular however any cos related equation but Sine related totally opposite

An alpha particle and a proton both having the same kinetic energy enter a region of uniform magnetic field both moving perpendicular to the direction of the field The ratio of the radius of the orbit of the proton to that of the alpha particle is A 4 B 2 C 1 D 1 2

7 A monkey of mass 20 kg rides on a 40 kg trolley moving at a constant speed of 8 m s along a horizontal track Frictional force can be neglected If the monkey jumps vertically with respect to the moving trolley to catch the hanging branch of tree the speed of the trolley after the monkey has jumped off is h 1 16m s 3 8m s 2 2 4 6m s 12m s ENTHUSE LEADER ACHIEVER ALPHA PLUS SPARK CRASH COURSE 1 H 06092021 7

A block of mass 2m is connected with a string which is wound over a pulley of mass m and radius R as shown in figure If the system is released from rest then angular acceleration of the pulley will be www A m R 2m 2g 5R 2g 3R 1

tile Motion 2 From the top of a 11 m high tower a stone is projected with speed 10 m s at an angle of 37 as shown in figure Find a Time of flight b Horizontal range c Speed just before striking the ground t 11 m 10 m s A

The electric field of a plane polarized electromagnetic wave in free space at time t 0 is given by an expression E x y 10 jcos 6x 8z The magnetic field B x z t is given by c is the velocity of light a 6k 81 cos 6x 8z 10ct b 6k 81 cos 6x 8z 10ct c 6k 81 cos 6x 8z 10ct 4 6 8ilcos 6x 8z 10ct JEE Main

Two blocks A and B are as shown in figure The minimum horizontal force F applied to the block B for which slipping just begins between B and ground is H 0 2 30 3 H 0 5 100 A B 10kg 20kg ON 7777 170

Light with an average flux of 20 W cm2 falls on non reflecting surface at normal incidence having surface area 20 cm The energy received by th surface during time span of 1 minute is 1 48 x 10 J 2 10 10 J 3 12 x 10 J 4 24 x 10 J

A particle is in equilibrium under the action of the six forces If three of these forces are reversed the particle still remains in the equilibrium Which of the given statement is are CORRECT A If any two of these six forces is removed it will be in equilibrium B If any one from three reversed forces is removed system will not be in equilibrium C If all these reversed forces are removed then particle will be in equilibrium D If all the three not reversed one forces are removed then particle will be in equilibrium