Practice Questions

Q11.A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to (1) x3 (2) ex (3) x (4) loge x

Q12.Which of the following statements is false for a particle moving in a circle with a constant angular speed? (1) The velocity vector is tangent to the circle. (2) The acceleration vector is tangent to the circle. (3) The acceleration vector points to the centre of the (4) The velocity and acceleration vectors are circle. perpendicular to each other.

Q13.A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table? (1) 7.2 J (2) 3.6 J (3) 120 J (4) 1200 J

Q14.A force →F = (5^i + 3^j + 2^k)N is applied over a particle which displaces it from its origin to the point →r = (2^i −^j)m. The work done on the particle in joules is (1) −7 (2) +7 (3) +10 (4) +13

Q15.A body of mass m, accelerates uniformly from rest to v1 in time t1 . The instantaneous power delivered to the body as a function of time t is JEE Main 2004 JEE Main Previous Year Paper (1) mv1t (2) mv21t t1 t21 (3) mv1t2 (4) mv21t t1 t1

Q16.A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that (1) its velocity is constant (2) its acceleration is constant (3) its kinetic energy is constant (4) it moves in a straight line.

Q17.A wire fixed at the upper end stretches by length by applying a force F. The work done in stretching is (1) F/2 (2) Fℓ (3) 2 Fℓ (4) Fℓ/2

Q18.A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which one of the following will not be affected? (1) moment of inertia (2) angular momentum (3) angular velocity (4) rotational kinetic energy.

Q19.One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively IA and IB such that (1) IA = IB (2) IA > IB (3) IA < IB (4) yes, 45∘IA/IB = dA/dB Where dA and dB are their densities.

Q20.A satellite of mass m revolves around the earth of radius R at a height x from its surface. If g is the acceleration due to gravity on the surface of the earth, the orbital speed of the satellite is (1) gx (2) gR R−x (3) g2 (4) gR2 1/2 R+x ( R+x )

Q21.The time period of an earth satellite in circular orbit is independent of (1) the mass of the satellite (2) radius of its orbit (3) both the mass and radius of the orbit (4) neither the mass of the satellite nor the radius of its orbit.

Q22.If g is the acceleration due to gravity on the earth's surface, the gain in the potential energy of object of mass m raised from the surface of the earth to a height equal to the radius R of the earth is (1) 2mgR (2) 21 mgR (3) 1 4 mgR (4) mgR

Q23.Suppose the gravitational force varies inversely as the nth power of distance. Then the time period planet in circular orbit of radius R around the sun will be proportional to (1) R( n+12 ) (2) R( n−12 ) (3) Rn (4) R( n−22 )

Q24.Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is JEE Main 2004 JEE Main Previous Year Paper (1) directly proportional to R but inversely (2) directly proportional to both radius R and proportional to v. velocity v. (3) inversely proportional to both radius R and (4) inversely proportional to R but directly velocity v. proportional to velocity v.

Q25.If two soap bubbles of different radii are connected by a tube, (1) air flows from the bigger bubble to the smaller (2) air flows from bigger bubble to the smaller bubble till the sizes are interchanged. bubble till the sizes are interchanged (3) air flows from the smaller bubble to the bigger. (4) there is no flow of air.

Q26.If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be (1) 4 (2) 16 (3) 32 (4) 64

Q27.The temperature of two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity K and 2K and thickness x and 4x, respectively are T2 and T1 (T2 > T1). The rate of heat f equal to transfer through the slab, in a steady state is ( A(T2−T1)Kx )f , with (1) 1 (2) 1/2 (3) 2/3 (4) 1/3

Q28.The thermistors are usually made of (1) metals with low temperature coefficient of (2) metals with high temperature coefficient of resistivity resistivity (3) metal oxides with high temperature coefficient of (4) semiconducting materials having low resistivity " temperature coefficient of resistivity.

Q29.Time taken by a 836 W heater to heat one litre of water from 10∘C to 40∘C is (1) 50 s (2) 100 s (3) 150 s (4) 200 s

Q30.The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = aθ + bθ2 in volts where the ratio a/b is 700∘C. If the cold junction is kept at 0∘C, then the neutral temperature is (1) 700∘C (2) 350∘C (3) 1400∘C (4) no neutral temperature is possible for this thermocouple. JEE Main 2004 JEE Main Previous Year Paper

Q32.One mole of ideal monoatomic gas (γ = 5/30) is mixed with one mole of diatomic gas (γ = 7/5). What is γ for the mixture? γ denotes the ratio of specific heat at constant pressure, to that at constant volume. (1) 3/2 (2) 23/15 (3) 35/23 (4) 4/3

Q33.Two thermally insulated vessels 1 and 2 are filled with air at temperatures (T1, T2), volume (V1, V2) and pressure (P1, P2) respectively. If the valve joining two vessels is opened, the temperature inside the vessel at equilibrium will be (1) T1 + T2 (2) (T1 + T2)/2 (3) T1 T2(P1 V1+P2 V2) (4) T1 T2(P1 V1+P2 V2) P1 V1 T2+P2 V2 T1 P1 V1 T1+P2 T2 T2

Q34.The bob of a simple pendulum executes simple harmonic motion in water with a period t, while the period of oscillation of the bob is t0 in air. Neglecting frictional force of water and given that the density of the bob is ( 43 ) × 1000 kg/m3 . What relationship between t and t0 is true? (1) t = t0 (2) t = t0/2 (3) t = 2t0 (4) t = 4t0

Q35.A particle at the end of a spring executes simple harmonic motion with a period t1 , while the corresponding period for another spring is t2 . If the period of oscillation with the two springs in series is t, then (1) T = t1 + t2 (2) ∝x2 (3) T−1 = t−11 + t−12 (4) T−2 = t21 + t22

Q37.A particle of mass m is attached to a spring (of spring constant k ) and has a natural angular frequency ω0 . An external force F(t) proportional to cos ωt (ω ≠ω0) is applied to the oscillator. The time displacement of the oscillator will be proportional to (1) m (2) 1 ω20−ω2 m(ω20−ω2) (3) 1 (4) m m(ω20+ω2) ω20+ω2