Practice Questions

Q3. A boy is rolling a 0. 5 kg ball on the frictionless floor with the speed of 20 m s−1. The ball gets deflected by an obstacle on the way. After deflection it moves with 5% of its initial kinetic energy. What is the speed of the ball now? (1) 19. 0 m s−1 (2) 4. 4 m s−1 (3) 14. 41 m s−1 (4) 1. 00 m s−1 →

Q3. Which of the following is not a dimensionless quantity? (1) Power factor (2) Quality factor (3) Permeability of free space (μ0) (4) Relative magnetic permeability (μr)

Q3. The ranges and heights for two projectiles projected with the same initial velocity at angles 42° and 48° with the horizontal are 𝑅1, 𝑅2 and 𝐻1, 𝐻2 respectively. Choose the correct option: (1) 𝑅1 = 𝑅2 and 𝐻1 = 𝐻2 (2) 𝑅1 = 𝑅2 and 𝐻1 < 𝐻2 (3) 𝑅1 > 𝑅2 and 𝐻1 = 𝐻2 (4) 𝑅1 < 𝑅2 and 𝐻1 < 𝐻2 JEE Main 2021 (01 Sep Shift 2) JEE Main Previous Year Paper

Q4. List- I List- II (a) MI of the rod (length L, Mass M, about an axis ⊥ to the rod passing (i) through the midpoint) 8ML2 3 (b) MI of the rod (length L, Mass 2M, about an axis ⊥ to the rod ML2 (ii) 3 passing through one of its end) (c) MI of the rod (length 2L, Mass M, about an axis ⊥ to the rod (iii) passing through its midpoint) ML2 12 (d) MI of the rod (Length 2L, Mass 2M, about an axis ⊥ to the rod (iv) passing through one of its end) 2ML2 3 Choose the correct answer from the options given below: JEE Main 2021 (27 Jul Shift 1) JEE Main Previous Year Paper (1) (a) −(ii), (b) −(iii), (c) −(i), (d) −(iv) (2) (a) −(ii), (b) −(i), (c) − (iii), (d) −(iv) (3) (a) −(iii), (b) −(iv), (c) − (ii), (d) −(i) (4) (a) − (iii), (b) −(iv), (c) −(i), (d) −(ii)

Q4. A boy reaches the airport and finds that the escalator is not working. He walks up the stationary escalator in time t1. If he remains stationary on a moving escalator then the escalator takes him up in time t2. The time taken by him to walk up on the moving escalator will be: (1) t1t2 (2) t1+t2 t2−t1 2 (3) t1t2 (4) t2 −t1 t2+t1

Q4. The maximum and minimum distances of a comet from the Sun are 1. 6 × 1012 m and 8. 0 × 1010 m respectively. If the speed of the comet at the nearest point is 6 × 104 m s−1 , the speed at the farthest point is (1) 1. 5 × 103 m s−1 (2) 6. 6 × 103 m s−1 (3) 3. 0 × 103 m s−1 (4) 4. 5 × 103 m s−1

Q4. A porter lifts a heavy suitcase of mass 80 kg and at the destination lowers it down by a distance of 80 cm with a constant velocity. Calculate the work done by the porter in lowering the suitcase. (take g = 9. 8 ms−2 ) (1) −62720. 0 J (2) −627. 2 J (3) +627. 2 J (4) 784. 0 J

Q4. A player kicks a football with an initial speed of 25 m s−1 at an angle of 45° from the ground. What are the maximum height and the time taken by the football to reach at the highest point during motion? (Take g = 10 m s−2 ) (1) hmax = 15. 625 m, T = 1. 77 s (2) hmax = 3. 54 m, T = 0. 125 s (3) hmax = 10 m, T = 2. 5 s (4) hmax = 15. 625 m, T = 3. 54 s

Q4. Consider two satellites 𝑆1 and 𝑆2 with periods of revolution 1hr and 8hr respectively revolving around a planet in circular orbits. The ratio of angular velocity of satellite 𝑆1 to the angular velocity of satellite 𝑆2 is: (1) 8: 1 (2) 2: 1 (3) 1: 4 (4) 1: 8

Q5. The instantaneous velocity of a particle moving in a straight line is given as v = αt + βt2 , where α and β are constants. The distance travelled by the particle between 1 s and 2 s is: (1) 3α + 7β (2) 32 α + 73 β (3) α 2 + β3 (4) 32 α + 72 β Q6. → A force F = + N acts on a body of mass 5 kg. If the body starts from rest, its position vector →rat (40ˆi 10ˆj) time t = 10 s will be + + m (1) (100ˆi 400ˆj) m (2) (100ˆi 100ˆj) + + m (3) (400ˆi 100ˆj) m (4) (400ˆi 400ˆj)

Q5. Angular momentum of a single particle moving with constant speed along circular path : (1) remains same in magnitude but changes in the (2) remains same in magnitude and direction direction (3) is zero (4) changes in magnitude but remains same in the direction

Q5. The time period of a satellite in a circular orbit of the radius R is T. The period of another satellite in a circular orbit of the radius 9R is: (1) 9T (2) 27T (3) 12T (4) 3T

Q5. A bomb is dropped by a fighter plane flying horizontally. To an observer sitting in the plane, the trajectory of the bomb is a : (1) straight line vertically down the plane (2) parabola in a direction opposite to the motion of plane (3) parabola in the direction of motion of plane (4) hyperbola

Q5. If the kinetic energy of a moving body becomes four times its initial kinetic energy, then the percentage change in its momentum will be: (1) 100% (2) 200% (3) 300% (4) 400%

Q6. A bimetallic strip consists of metals A and B. It is mounted rigidly as shown. The metal A has higher coefficient of expansion compared to that of metal B. When the bimetallic strip is placed in a cold both, it will : (1) Bend towards the right (2) Not bend but shrink (3) Neither bend nor shrink (4) Bend towards the left

Q6. On the basis of kinetic theory of gases, the gas exerts pressure because its molecules: (1) continuously stick to the walls of container. (2) suffer change in momentum when impinge on the walls of container. (3) continuously lose their energy till it reaches wall. (4) are attracted by the walls of container.

Q6. A planet revolving in elliptical orbit has : A. a constant velocity of revolution. B. has the least velocity when it is nearest to the sun. C. its areal velocity is directly proportional to its velocity. D. areal velocity is inversely proportional to its velocity. E. to follow a trajectory such that the areal velocity is constant. Choose the correct answer from the options given below: (1) A only (2) C only (3) E only (4) D only

Q6. Two identical springs of spring constant 2k are attached to a block of mass m and to fixed support (see figure). When the mass is displaced from equilibrium position on either side, it executes simple harmonic motion. The time period of oscillations of this system is : (1) π√mk (2) 2π√m2k (3) π√m2k (4) 2π√mk

Q7. In thermodynamics, heat and work are : (1) Path functions (2) Intensive thermodynamic state variables (3) Extensive thermodynamic state variables (4) Point functions

Q7. Two identical metal wires of thermal conductivities K1 and K2 respectively are connected in series. The effective thermal conductivity of the combination is: (1) 2 K1 K2 (2) K1+K2 K1+K2 2 K1 K2 (3) K1+K2 (4) K1 K2 K1 K2 K1+K2

Q7. What will be the average value of energy along one degree of freedom for an ideal gas in thermal equilibrium at a temperature T ? ( kB is Boltzmann constant) (1) 2 1 kBT (2) 32 kBT (3) 3 kBT (4) kBT 2

Q7. The R.M.S. speeds of the molecules of Hydrogen, Oxygen, and Carbon dioxide at the same temperature are vH, vO and vC respectively, then: (1) vC > vO > vH (2) vH = vO > vC (3) vH > vO > vC (4) vH = vO = vC

Q7. What will be the average value of energy for a monoatomic gas in thermal equilibrium at temperature T? (1) 2 3 kBT (2) kBT (3) 2 3 kBT (4) 21 kBT

Q7. Two different metal bodies 𝐴 and 𝐵 of equal mass are heated at a uniform rate under similar conditions. The variation of temperature of the bodies is graphically represented as shown in the figure. The ratio of specific heat capacities is: JEE Main 2021 (25 Jul Shift 1) JEE Main Previous Year Paper 8 3 (1) (2) 3 8 (3) 3 (4) 4 4 3

Q7. The angular momentum of a planet of mass M moving around the sun in an elliptical orbit is L. The magnitude of the areal velocity of the planet is : JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper (1) 4L (2) L M M (3) 2L (4) L M 2M