# JEE Main Practice Questions in Physics

Model Questions are given below for Physics subject. These are very much useful for the candidates going to appear for JEE Main Examinations in 2013 or later. The model questions were given along with key for the benefit of the students.

1. A liquid with volume expansion coefficient γ is filled in a container of material having linear expansion coefficient α. The liquid is found to over flow, when the temperature decreases by θo. Then
A) γ > 3α B) g > α C) g < 3α D) g < α 2. Two metal rods, A and B, have lengths l and 3l and linear expansion coefficient α and 2 α respectively. When the temperature decreases by θo C, it is found that their lengths are equal. Then A) α θ = 1/5 B) 2α θ = 5 C) 5α θ = 2 D) 5α θ = 3 3. An iron tyre is to be fitted onto a wooden wheel 1 m in diameter. The diameter of the tyre is 6 mm smaller than that of the wheel. The temperature of the tyre should be increased by a minimum (α = 3.6 × 10-5 oC-1 for iron). A) 1000 oC B) 334 oC C) 500 oC D) 167 oC 4. A metal sphere is heated. On thermal expansion, the smallest percentage increase will occur in its A) diameter B) volume C) surface area D) density 6. A particle is projected from point A with velocity u at an angle α with horizontal. In its parabolic path, at point P the particle is moving at right angles to its initial direction of projection. Its velocity at P is A) u tan α B) u cot α C) u cos α D) u cosec α 7. The angular speed of the second’s hand of a clock is A) (1/60) rad/s B) (π/60) rad/s C) (2π/60) rad/s D) (360/60) rad/s 8. A particle moves in a circle of radius 25 cm at two revolution per sec. The acceleration of the particle in m/s2 is A) π2 B) 8π2 C) 4π2 D) 2π2 9. A motor car is travelling at 60 m/s on a circular road of radius 1200 m. It is increasing its speed at the rate of 4 m/s2. The acceleration of the car is A) 3 m/s2 B) 4 m/s2 C) 5 m/s2 D) 7 m/s2 10. In a thermo dynamical process pressure of fixed mass of gas is changed in such a way that the gas molecules give out 30 J of heat and 10 J of work is done on the gas. If the internal energy of the gas was 40 J, the final internal energy will be A) zero B) 80 J C) 20 J D) – 20 J 11. A body travelling along a straight line traversed one third of the total distance with a velocity 4 m/s. The remaining part of the distance was covered with a velocity 2 m/s for half the time and with velocity 6 m/s for the other half of time. The mean velocity averaged over the whole time of motion is A) 5 m/s B) 4 m/s C) 4.5 m/s D) 3.5m/s 12. A ball is projected upwards from the foot of a tower. The ball crosses the top of the tower after an interval of 6s and the ball reaches the ground after 12s. The height of the tower (g = 10 m/s2) A) 120 m B) 135 m C) 175 m D) 80 m 16. A particle is projected from a horizontal plane (x-z plane). Such that its velocity vectors at time t is given by→ v = a i Λ + (b-ct) j Λ . Its range on the horizontal plane is A) ba/c B) 2ba/c C) 3ba/c D) none 17. A body is placed on a rough inclined plane of inclination θ. As the angle θ is increased from 0o to 90o the contact force between the block and the plane A) remains constant B) first remains constant then decreases C) first decreases then increases D) first increases then decreases 18. A flexible chain of weight W hangs between two fixed points A and B, which are at the same horizontal level. The inclination of the chain with the horizontal at both the points of support is θ. What is the tension of the chain at the mid point W W A) ___ cosec θ B) ___ tan θ 2 2 W C) ___ cot θ D) none 22. A particle of mass 1 kg is projected at an angle of 30o with horizontal with velocity v = 40 m/s. The change in linear momentum of the particle after time t = 1 s will be (g = 10 m/s2) A) 7.5 kg-m/s B) 15 kg-m/s C) 10 kg-m/s D) 20 kg-m/s 23. The centre of mass of a nonuniform rod of length L whose mass per unit length λ = Kx2/L, where K is a constant and x is the distance from one end is A) 3L/4 B) L/8 C) K/L D) 3K/l 24. From a circular disc of radius R a square is cut out with a radius as its diagonal. The distance of the centre of mass of the remainder from the centre of the disc is R R A) ______ B) ______ π - 2 π R R C) ______ D) ______ 2(2π - 1) 2 KEY : 1)C 2)C 3)D 4)A 5)C 6)B 7)C 8)C 9)C 10)C 11)B 12)B 13)B 14)C 15)D 16)B 17)B 18)C 19)C 20)C 21)A 22)C 23)A 24)C 25)B 26)A 27)A 28)C 29)B 30)C 31)C 32)B 33)D.