Practice Questions

Q7. A steel wire of length 3. 2 m(YS = 2. 0 × 1011 N m−2) and a copper wire of length 4. 4 m (YC = 1. 1 × 1011 N m−2) , both of radius 1. 4 mm are connected end to end. When stretched by a load, the net elongation is found to be 1. 4 mm. The load applied, in Newton, will be: (Given π = 227 ) (1) 360 (2) 180 (3) 1080 (4) 154

Q11.An aluminium wire is stretched to make its length, 0. 4% larger. The percentage change in resistance is (1) 0. 4% (2) 0. 2% (3) 0. 8% (4) 0. 6%

Q12.A compass needle of oscillation magnetometer oscillates 20 times per minute at a place P of dip 30° . The number of oscillations per minute become 10 at another place Q of 60° dip. The ratio of the total magnetic field at the two places (BQ : BP) is: (1) √3 : 4 (2) 4 : √3 (3) √3 : 2 (4) 2 : √3 JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper

Q13.A cyclotron is used to accelerate protons. If the operating magnetic field is 1. 0 T and the radius of the cyclotron 'dees' is 60 cm, the kinetic energy of the accelerated protons in MeV will be : [use mp = 1. 6 × 10−27 kg, e = 1. 6 × 10−19 C] (1) 12 (2) 18 (3) 16 (4) 32

Q14.The magnetic flux through a coil perpendicular to its plane is varying according to the relation ϕ = (5t3 + 4t2 + 2t −5) Weber. If the resistance of the coil is 5 ohm , then the induced current through the coil at t = 2 s will be, (1) 15. 6 A (2) 16. 6 A (3) 17. 6 A (4) 18. 6 A

Q16.Two coherent sources of light interfere. The intensity ratio of two sources is 1 : 4. For this interference pattern if the value of Imax+Imin is equal to 2α+1 , then α will be Imax−Imin β+3 β (1) 1. 5 (2) 2 (3) 0. 5 (4) 1

Q18.How many alpha and beta particles are emitted when Uranium 92U238 decays to lead 82 Pb206 ? (1) 3 alpha particles and 5 beta particles (2) 6 alpha particles and 4 beta particles (3) 4 alpha particles and 5 beta particles (4) 8 alpha particles and 6 beta particles

Q21.A uniform chain of 6 m length is placed on a table such that a part of its length is hanging over the edge of the table. The system is at rest. The co-efficient of static friction between the chain and the surface of the table is 0 . 5, the maximum length of the chain hanging from the table is _____ m.

Q21.Two inclined planes are placed as shown in figure. A block is projected from the Point A of inclined plane AB along its surface with a velocity just sufficient to carry it to the top Point B at a height 10 m. After reaching the Point B the block slides down on inclined plane + BC . Time it takes to reach to the point C from point A is t(√2 1)s. The value of t is _____ (use g = 10 m s−2 )

Q21.The moment of inertia of a uniform thin rod about a perpendicular axis passing through one end is I1 . The x same rod is bent into a ring and its moment of inertia about a diameter is I2 . If I2I1 is xπ23 , then the value of will be ______.

Q21.A body is projected from the ground at an angle of 45° with the horizontal. Its velocity after 2 s is 20 m s−1 . The maximum height reached by the body during its motion is _____ m . (use g = 10 m s−2 )

Q21.As per the given figure, two plates A and B of thermal conductivity K and 2K are joined together to form a compound plate. The thickness of plates are 4. 0 cm and 2. 5 cm respectively and the area of cross-section is 120 cm2 for each plate. The equivalent thermal conductivity of the compound plate is (1 + α5 )K , then the value of α will be _____ . Q22. 300 calories of heat is given to a heat engine, and it rejects 225 calories of heat. If source temperature is 227°C, then the temperature of sink will be _____ ∘C.

Q21.A particle is moving in a straight line such that its velocity is increasing at 5 m s−1 per meter. The acceleration of the particle is _____ m s−2 at a point where its velocity is 20 m s−1 .

Q21.A hanging mass M is connected to a four times bigger mass by using a string pulley arrangement, as shown in the figure. The bigger mass is placed on a horizontal ice-slab and being pulled by 2 Mg force. In this situation, tension in the string is x 5 Mg for x =_____. Neglect mass of the string and friction of the block (bigger mass) with ice slab. (Given g = acceleration due to gravity)

Q21.A mass of 10 kg is suspended vertically by a rope of length 5 m from the roof. A force of 30 N is applied at the middle point of rope in horizontal direction. The angle made by upper half of the rope with vertical is α = tan−1(x × 10−1). The value of x is _____ . (Given, g = 10 m s−2 ) JEE Main 2022 (27 Jun Shift 2) JEE Main Previous Year Paper

Q21.In an experiment to find acceleration due to gravity (g) using simple pendulum, time period of 0. 5 s is measured from time of 100 oscillation with a watch of 1 s resolution. If measured value of length is 10 cm known to 1 mm accuracy. The accuracy in the determination of g is found to be x%. The value of x is

Q21.A tube of length 50 cm is filled completely with an incompressible liquid of mass 250 g and closed at both ends. The tube is then rotated in horizontal plane about one of its ends with a uniform angular velocity 𝑥√𝐹 rad s-1. If 𝐹 be the force exerted by the liquid at the other end then the value of 𝑥 will be _____ .

Q21.An object is projected in the air with initial velocity u at an angle θ. The projectile motion is such that the horizontal range R, is maximum. Another object is projected in the air with a horizontal range half of the range of first object. The initial velocity remains same in both the case. The value of the angle of projection, at which the second object is projected, will be _____ degree.

Q21.A ball is projected vertically upward with an initial velocity of 50 m s−1 at t = 0 s. At t = 2 s, another ball is projected vertically upward with same velocity. At t =____ s, second ball will meet the first ball (g = 10 m s−2) .

Q22.If the acceleration due to gravity experienced by a point mass at a height h above the surface of earth is same as that of the acceleration due to gravity at a depth αh(h ≪Re) ) from the earth surface. The value of α will be _____ . (use Re = 6400 km)

Q22.A ball is thrown vertically upwards with a velocity of 19. 6 m s−1 from the top of a tower. The ball strikes the ground after 6 s. The height from the ground up to which the ball can rise will be ( k5 ) m. The value of k is _____ (use g = 9. 8 m s−2 )

Q22.A fighter jet is flying horizontally at a certain altitude with a speed of 200 m s−1 . When it passes directly overhead an anti-aircraft gun, a bullet is fired from the gun, at an angle θ with the horizontal, to hit the jet. If the bullet speed is 400 m s−1 , the value of θ will be _____ °.

Q22.A block of mass '𝑚' (as shown in figure) moving with kinetic energy 𝐸 compresses a spring through a distance 25 cm when, its speed is halved. The value of spring constant of used spring will be 𝑛𝐸 N m-1 for 𝑛= _____.

Q22.A metal wire of length 0 . 5 m and cross-sectional area 10-4 m2 has breaking stress 5 × 108 N m-2. A block of 10 kg is attached at one end of the string and is rotating in a horizontal circle. The maximum linear velocity of block will be _____ m s-1.

Q22.A pulley of radius 1. 5 m is rotated about its axis by a force F = (12t −3t2) N applied tangentially (while t is measured in seconds). If moment of inertia of the pulley about its axis of rotation is 4. 5 kg m2 , the number of rotations made by the pulley before its direction of motion is reversed, will be K . The value of K is _____ . π