Practice Questions

Q19.A particle of mass m moves along line PC with velocity v as shown. What is the angular momentum of the particle about P? (1) mvL (2) mvl (3) mvr (4) zero

Q20.The kinetic energy needed to project a body of mass m from the earth surface (radius R ) to infinity is (1) mgR/2 (2) 2mgR (3) mgR (4) mgR/4

Q21.If suddenly the gravitational force of attraction between Earth and a satellite revolving around it becomes zero, then the satellite will (1) continue to move in its orbit with same velocity (2) move tangentially to the originally orbit in the same velocity (3) become stationary in its orbit (4) move towards the earth.

Q22.Energy required to move a body of mass m from an orbit of radius 2R to 3R is (1) GMm/12R2 (2) GMm/3R2 (3) GMm/8R (4) GMm/6R

Q23.The escape velocity of a body depends upon mass as (1) m0 (2) m1 (3) m2 (4) m3 JEE Main 2002 JEE Main Previous Year Paper

Q24.A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in ms−1 ) through a small hole on the side wall of the cylinder near its bottom is (1) 10 (2) 20 (3) 25.5 (4) 5

Q25.Heat given to a body which raises its temperature by 1∘C is (1) water equivalent (2) thermal capacity (3) specific heat (4) temperature gradient

Q26.Which of the following is more closed to a black body? (1) black board paint (2) green leaves (3) black holes (4) red roses

Q27.Two spheres of the same material have radii 1 m and 4 m and temperatures 4000 K and 2000 K respectively. The ratio of the energy radiated per second by the first sphere to that by the second is (1) 1 : 1 (2) 16 : 1 (3) 4 : 1 (4) 5 : 3

Q28.If θi , is the inversion temperature, θn is the neutral temperature, θc is the temperature of the cold junction, then (1) θi + θc = θn (2) θi −θc = 2θn (3) θi+θc 2 = θn (4) θc −θi = 2θn

Q29.Which statement is incorrect? (1) all reversible cycles have same efficiency (2) reversible cycle has more efficiency than an irreversible one (3) Carnot cycle is a reversible one (4) Carnot cycle has the maximum efficiency in all cycles

Q30.Even Carnot engine cannot give 100% efficiency because we cannot (1) prevent radiation (2) find ideal sources (3) reach absolute zero temperature (4) eliminate friction

Q31.Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will (1) increase (2) decrease (3) remain same (4) decrease for some, while increase for others

Q32.At what temperature is the r.m.s. velocity of a hydrogen molecule equal to that of an oxygen molecule at 47∘C ? (1) 80 K (2) 73 K (3) 3 K (4) 20 K Q33.1 mole of a gas with γ = 7/5 is mixed with 1 mole of a gas with γ = 5/3, then the value of γ for the resulting mixture is (1) 7/5 (2) 2/5 (3) 24/16 (4) 12/7 JEE Main 2002 JEE Main Previous Year Paper

Q34.In a simple harmonic oscillator, at the mean position (1) kinetic energy is minimum, potential energy is (2) both kinetic and potential energies are maximum maximum (3) kinetic energy is maximum, potential energy is (4) both kinetic and potential energies are minimum minimum

Q35.If a spring has time period T, and is cut into n equal parts, then the time period of each part will be (1) T√n (2) T/√n (3) nT (4) T

Q36.A child swinging on a swing in sitting position, stands up, then the time period of the swing will (1) increase (2) decrease (3) remains same (4) increases if the child is tall and decreases if the child is short

Q37.Length of a string tied to two rigid supports is 40 cm. Maximum length (wave length in cm ) of a stationary wave produced on it is (1) 20 (2) 80 (3) 40 (4) 120

Q38.Tube A has both ends open while tube B has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube A and B is (1) 1 : 2 (2) 1 : 4 (3) 2 : 1 (4) 4 : 1

Q39.A tuning fork arrangement (pair) produces 4 beats / sec with one fork of frequency 288cps. A little wax is placed on the unknown fork and it then produces 2 beats /sec. The frequency of the unknown fork is (1) 286 cps (2) 292 cps (3) 294 cps (4) 288 cps

Q40.A wave y = a sin(ωt −kx) on a string meets with another wave producing a node at x = 0. Then the equation of the unknown wave is (1) y = a sin(ωt + kx) (2) y = −a sin(ωt + kx) (3) y = a sin(ωt −kx) (4) y = −a sin(ωt −kx)

Q41.When temperature increases, the frequency of a tuning fork (1) increases (2) decreases (3) remains same (4) increases or decreases depending on the material

Q42.On moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is (1) 0.1 V (2) 8 V (3) 2 V (4) 0.5 V JEE Main 2002 JEE Main Previous Year Paper

Q43.A charged particle q is placed at the centre O of cube of length L (A B C D E F G H). Another same charge q is placed at a distance L from O. Then the electric flux through ABCD is (1) q/4πϵ0L (2) zero (3) q/2πϵ0L (4) q/3πϵ0L

Q44.If a charge q is placed at the centre of the line joining two equal charges Q such that the system is in equilibrium then the value of q is (1) Q/2 (2) −Q/2 (3) Q/4 (4) −Q/4