Practice Questions

Q3. The physical quantities not having same dimensions are (1) torque and work (2) momentum and Planck's constant (3) stress and Young's modulus (4) speed and (μ0ε0)−1/2

Q4. A car, moving with a speed of 50 km/hr, can be stopped by brakes after at least 6 m. If the same car is moving at a speed of 100 km/hr, the minimum stopping distance is (1) 12 m (2) 18 m (3) 24 m (4) 6 m

Q6. A body travels a distance s in t seconds. It starts from rest and ends at rest. In the first part of the journey, it moves with constant acceleration f and in the second part with constant retardation r. The value of t is given by (2) 2s ( f1 + 1r ) f 1 + 1r ) (1) √2s ( (3) 1 2 s 1 (4) √2s(f + r) f + r

Q8. A boy playing on the roof of a 10 m high building throws a ball with a speed of 10 m/s at an angle of 30∘ with the horizontal. How far from the throwing point will the ball be at the height of 10 m from the ground? 1 √3 = 10 m/s2, sin 30∘= , cos 30∘= 2 2 [g ] (1) 5.20 m (2) 4.33 m (3) 2.60 m (4) 8.66 m JEE Main 2003 JEE Main Previous Year Paper

Q12.A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The co-efficient of friction between the block and the wall is 0.2 . The weight of the block is (1) 20 N (2) 50 N (3) 100 N (4) 2 N

Q13.A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10 s. Then the coefficient of friction is (1) 0.02 (2) 0.03 (3) 0.04 (4) None of these

Q14.A block of mass M is pulled along a horizontal frictionless surface by a rope of mass m. If a force P is applied at the free end of the rope, the force exerted by the rope on the block is (1) Pm (2) Pm M+m M−m (3) P (4) PM M+m JEE Main 2003 JEE Main Previous Year Paper

Q17.Consider the following two statements: (A) Linear momentum of a system of particles is zero (B) Kinetic energy of a system of particles is zero Then (1) A does not imply B and B does not imply A (2) A implies B but B does not imply A (3) A does not imply B but B implies A (4) A implies B and B implies A

Q18.A spring of spring constant 5 × 103 N/m is stretched initially by 5 cm from the unstretched position. Then the work required to stretch it further by another 5 cm is (1) 12.50 N −m (2) 18.75 N −m (3) 25.00 N −m (4) 6.25 N −m

Q19.A body is moved along a straight line by a machine delivering a constant power. The distance moved by the body in time ' t ' is proportional to (1) t3/4 (2) t3/2 (3) t1/4 (4) t1/2

Q20.A circular disc X of radius R is made from an iron plate of thickness t, and another disc Y of radius 4R is made from an iron plate of thickness t . Then the relation between the moment of inertia IX and IY is 4 (1) IY = 32Ix (2) IY = 16Ix (3) IY = IX (4) IY = 64IX

Q24.Two spherical bodies of mass M and 5M& radii R&2R respectively are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body just before collision is (1) 2.5R (2) 4.5R (3) 7.5R (4) 1.5R

Q32.During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio Cp/Cv for the gas is JEE Main 2003 JEE Main Previous Year Paper (1) 4 (2) 2 3 (3) 5 (4) 3 3 2

Q33.In the nuclear fusion reaction 21H + 31H →42He + n given that the repulsive potential energy between the two nuclei is ∼7.7 × 10−14 J, the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann's Constant k = 1.38 × 10−23 J/K ] (1) 107 K (2) 105 K (3) 103 K (4) 109 K

Q34.A mass M is suspended from a spring of negligible mass. The spring is pulled a little and then released so that the mass executes SHM of time period T. If the mass is increased by m, the time period becomes 53T . Then the ratio of Mm is (1) 53 (2) 259 (3) 16 (4) 5 9 3

Q35.Two particles A and B of equal masses are suspended from two massless springs of spring constant k1 and k2 , respectively. If the maximum velocities, during oscillation, are equal, the ratio of amplitude of A and B is (1) (2) k2 k1 √k1k2 k2 (3) √k2k1 (4) k1

Q39.A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of a piano. The beat frequency decreases to 2 beats per second when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was (1) 256 + 2 Hz (2) 256 −2 Hz (3) 256 −5 Hz (4) 256 + 5 Hz

Q41.A thin spherical conducting shell of radius R has a charge q. Another charge Q is placed at the centre of the shell. The electrostatic potential at a point P a distance R2 from the centre of the shell is (1) 2Q (2) 2Q − 2q 4πε0R 4πε0R 4πε0R (3) 2Q + q (4) (q+Q)2 4πε0R 4πε0R 4πε0R

Q42.Three charges −q1, +q2 and −q3 are placed as shown in the figure. The x-component of the force on −q1 is proportional to (1) q2 −q3 cos θ (2) q2 + q3 sin θ b2 a2 b2 a2 (3) q2 + q3 cos θ (4) q2 −q3 sin θ b2 a2 b2 a2

Q45.The length of a wire of a potentiometer is 100 cm, and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5Ω. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is (1) 30E (2) 30E 100.5 (100−0.5) (3) 30(E−0.5i) , where i is the current in the (4) 30E100 100 potentiometer wire

Q47.The thermo e.m.f. of a thermo-couple is 25μV/∘C at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as 10−5 A, is connected with the thermo couple. The smallest temperature JEE Main 2003 JEE Main Previous Year Paper difference that can be detected by this sytem is (1) 16∘C (2) 12∘C (3) 80C (4) 20∘C

Q48.The negative Zn pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is (1) 0.180 g (2) 0.141 g (3) 0.126 g (4) 0.242 g

Q49.An ammeter reads up to 1 ampere. Its internal resistance is 0.81ohm. To increase the range to 10 A the value of the required shunt is (1) 0.03Ω (2) 0.3Ω (3) 0.9Ω (4) 0.09Ω

Q50.A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The current I, in the circuit will be (1) 1 A (2) 1.5 A (3) 2 A (4) 1/3 A

Q51.A 220 volt, 1000 watt bulb is connected across a 110 volt mains supply. The power consumed will be (1) 750watt (2) 500watt (3) 250watt (4) 1000watt