Practice Questions

Q8. The escape velocity of a body on a planet A is 12 km s−1 . The escape velocity of the body on another planet B, whose density is four times and radius is half of the planet A , is (1) 12 km s−1 (2) 24 km s−1 (3) 36 km s−1 (4) 6 km s−1

Q8. A lead bullet penetrates into a solid object and melts. Assuming that 40% of its kinetic energy is used to heat it, the initial speed of bullet is (Given, initial temperature of the bullet = 127°C, Melting point of the bullet = 327°C, Latent heat of fusion of lead = 2. 5 × 104 J kg−1 , Specific heat capacity of lead = 125 J kg K−1 ) (1) 125 m s−1 (2) 500 m s−1 (3) 250 m s−1 (4) 600 m s−1

Q8. Two metallic blocks M1 and M2 of same area of cross-section are connected to each other (as shown in figure). If the thermal conductivity of M2 is K then the thermal conductivity of M1 will be : [Assume steady state heat conduction] JEE Main 2022 (24 Jun Shift 1) JEE Main Previous Year Paper (1) 10K (2) 8K (3) 12. 5K (4) 2K

Q8. A drop of liquid of density ρ is floating half immersed in a liquid of density σ and surface tension 7. 5 × 10−4 N cm−1 . The radius of drop in cm will be : (Take : g = 10 ms−2 ) (1) 15 (2) 15 √2ρ−σ √ρ−σ (3) 3 (4) 3 2√ρ−σ 20√2ρ−σ

Q8. Two metallic plates form a parallel plate capacitor. The distance between the plate is '𝑑'. A metal sheet of 𝑑 thickness and of area equal to area of each plate is introduced between the plates. What will be the ratio of the 2 JEE Main 2022 (25 Jun Shift 2) JEE Main Previous Year Paper new capacitance to the original capacitance of the capacitor? (1) 1: 2 (2) 2: 1 (3) 1: 4 (4) 4: 1

Q8. A gas has 𝑛 degrees of freedom. The ratio of specific heat of gas at constant volume to the specific heat of gas at constant pressure will be 𝑛 𝑛+ 2 (1) (2) 𝑛+ 2 𝑛 (3) 𝑛 (4) 𝑛 2𝑛+ 2 𝑛- 2

Q8. In 1stmsup case, Carnot engine operates between temperatures 300 K and 100 K . In 2ndmsup case, as shown in the figure, a combination of two engines is used. The efficiency of this combination (in 2ndmsup case) will be : JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper (1) same as the 1st case (2) always greater than the 1st case (3) always less than the 1st case (4) may increase or decrease with respect to the 1st case

Q8. For a specific wavelength 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670. 7 nm. The value of v is (1) 3 × 108 m s−1 (2) 3. 13 × 105 m s−1 (3) 3 × 1010 m s−1 (4) 4. 48 × 105 m s−1

Q8. In the figure, a very large plane sheet of positive charge is shown. 𝑃1 and 𝑃2 are two points at distance 𝑙 and 2𝑙 from the charge distribution. If 𝜎 is the surface charge density, then the magnitude of electric fields 𝐸1 and 𝐸2 at 𝑃1 and 𝑃2 respectively are JEE Main 2022 (25 Jun Shift 1) JEE Main Previous Year Paper 𝜎 𝜎 2𝜎 𝜎 (1) 𝐸1 = 𝜀𝑜, 𝐸2 = 2𝜀𝑜 (2) 𝐸1 = 𝜀𝑜, 𝐸2 = 𝜀𝑜 𝜎 𝜎 (3) 𝐸1 = 𝐸2 = (4) 𝐸1 = 𝐸2 = 2𝜀𝑜 𝜀𝑜

Q8. Following statements are given (1) The average kinetic energy of a gas molecule decreases when the temperature is reduced. (2) The average kinetic energy of a gas molecule increases with increase in pressure at constant temperature. (3) The average kinetic energy of a gas molecule decreases with increases in volume. (4) Pressure of a gas increases with increase in temperature at constant volume. (5) The volume of gas decreases with increase in temperature. Choose the correct answer from the options given below : (1) (1) and (4) only (2) (1), (2) and (4) only (3) (2) and (4) only (4) (1), (2) and (5) only

Q8. A thermally insulated vessel contains an ideal gas of molecular mass M and ratio of specific heats 1. 4. Vessel is moving with speed v and is suddenly brought to rest. Assuming no heat is lost to the surrounding and vessel temperature of the gas increases by : ( R = universal gas constant) (1) Mv2 (2) Mv2 7R 5R (3) 2 Mv27R (4) 7 Mv25R

Q9. Two metallic wires of identical dimensions are connected is series. If σ1 and σ2 are the conductivities of the these wires respectively, the effective conductivity of the combination is : (1) σ1σ2 (2) 2σ1σ2 σ1+σ2 σ1+σ2 (3) σ1+σ2 (4) σ1+σ2 2σ1σ2 σ1σ2

Q9. A mixture of hydrogen and oxygen has volume 2000 cm3 , temperature 300 K, pressure 100 kPa and mass 0. 76 g . The ratio of number of moles of hydrogen to number of moles of oxygen in the mixture will be [Take gas constant R = 8. 3 J K−1 mol−1 ] (1) 1 (2) 3 3 1 (3) 1 (4) 16 16 1

Q9. A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat during BC and rejects 60 J of heat during CA. A work of 50 J is done on the gas during the part BC . The internal energy of the gas at A is 1560 J. The work done by the gas during the part CA is (1) 20 J (2) 30 J (3) −30 J (4) −60 J

Q9. A vessel contains 16 g of hydrogen and 128 g of oxygen at standard temperature and pressure. The volume of the vessel in cm3 is : (1) 72 × 105 (2) 32 × 105 (3) 27 × 104 (4) 54 × 104

Q9. A teacher in his physics laboratory allotted an experiment to determine the resistance 𝐺 a galvanometer. 1 Students took the observations for deflection in the galvanometer. Which of the below is true for measuring 3 value of 𝐺? (1) 1 deflection method cannot be used for (2) 1 deflection method can be used and in this case 3 3 determining the resistance of the galvanometer. the 𝐺 equals to twice the value of shunt resistance(s). 1 1 (3) deflection method can be used and in this case, (4) deflection method can be used and in this case 3 3 the G equals to three times the value of shunt the 𝐺 value equals to the shunt resistance(s) resistance(s).

Q9. The velocity of sound in a gas, in which two wavelengths 4. 08 m and 4. 16 m produce 40 beats in 12 s , will be (1) 282. 8 m s−1 (2) 175. 5 m s−1 (3) 353. 6 m s−1 (4) 707. 2 m s−1

Q9. When a particle executes simple Harmonic motion, the nature of graph of velocity as function of displacement will be (1) Circular (2) Ellipitical (3) Sinusoidal (4) Straight line

Q9. Two massless springs with spring constants 2k and 9k, carry 50 g and 100 g masses at their free ends. These two masses oscillate vertically such that their maximum velocities are equal. Then, the ratio of their respective JEE Main 2022 (24 Jun Shift 2) JEE Main Previous Year Paper amplitudes will be : (1) 3 : 2 (2) 1 : 2 (3) 3 : 1 (4) 2 : 3

Q9. A wire of length L is hanging from a fixed support. The length changes to L1 and L2 when masses 1 kg and 2 kg are suspended respectively from its free end. Then the value of L is equal to (1) √L1 L2 (2) L1+L22 (3) 2L1 −L2 (4) 3L1 −L2

Q9. A Carnot engine whose heat sinks at 27°C, has an efficiency of 25%. By how many degrees should the temperature of the source be changed to increase the efficiency by 100% of the original efficiency ? (1) Increases by 18°C (2) Increases by 200°C (3) Increases by 120°C (4) Increases by 73°C

Q9. In figure (A), mass 2𝑚 is fixed on mass 𝑚 which is attached to two springs of spring constant 𝑘. In figure (B), mass 𝑚 is attached to two spring of spring constant 𝑘 and 2𝑘. If mass 𝑚 in (A) and (B) are displaced by distance 𝑥 horizontally and then released, then time period 𝑇1 and 𝑇2 corresponding to (A) and (B) respectively follow the relation. 𝑇1 3 𝑇1 3 (1) (2) = √2 𝑇2 = √ 2 𝑇2 2 √2 (3) 𝑇1 (4) 𝑇1 = = √ 3 3 𝑇2 𝑇2

Q9. Let η1 is the efficiency of an engine at T1 = 447°C and T2 = 147°C while η2 is the efficiency at T1 = 947°C and T2 = 47°C. The ratio η2η1 will be (1) 0. 41 (2) 0. 56 (3) 0. 73 (4) 0. 70

Q9. The root mean square speed of smoke particles of mass 5 × 10-17 kg in their Brownian motion in air at NTP is approximately. [Given 𝑘= 1 . 38 × 10-23J K-1] (1) 60 mm s-1 (2) 12 mm s-1 (3) 15 mm s-1 (4) 36 mm s-1

Q9. Two cells of the same EMF 𝐸 but different internal resistances 𝑟1 and 𝑟2 are connected in series with an external resistance 𝑅 as shown in the figure. The terminal potential difference across, the second cell is found to be zero. The external resistance 𝑅 must then be: (1) 𝑟1𝑟2 (2) 𝑟1 - 𝑟2 (3) 𝑟2 - 𝑟1 (4) 𝑟1 + 𝑟2