NEET TEST SERIES 103 PHYSICS

3. The mass and volume of a body are 4.237g and 2.5 cm respectively. The density of the material of the body (in g/cm³) in correct significant figure is

a) 1.6048

b) 1.69

c) 1.695

d) 1.7

4. Four marbles are dropped from the top of a tower, one after the other with an interval of one second. The first one reaches the ground after 4 second. When the first one reaches the ground, the distances between the first and second, the second and third and the third and fourth will be, respectively

a) 35 m, 25 m and 15 m            
b) 30 m, 25 m and 10 m
c) 35 m, 20 m and 15 m
d) 30 m, 20 m and 10 m

5. A particle is moving in a straight line and its acceleration-time graph is shown below. At t = 0 the particle has velocity (–10 m/s). Find the velocity of the particle at t = 8 s

a) 20 m/s
b) 30 m/s
c) 40 m/s
d) 50 m/s

6. A point mass moves along a circle of radius R with a constant angular acceleration α. How much time is needed after motion begins for the radial acceleration of the point mass to be equal to its tangential acceleration?

7. A string of length 10 cm breaks if its tension exceeds 10 N. A stone of mass 250 gm tied to this string, is rotated in a horizontal circle. The maximum angular velocity of rotation can be

a) 20 rad/s
b) 10 rad/s
c) 30 rad/s
d) 50 rad/s

8. A body of mass 10 kg is released from a tower of height 20 m and body acquires a velocity of 10 m/s after falling through the distance 20 m. The work done by the push of the air on the body is (Take g = 10 m/s)

a) 1500 J
b) 1800 J
c) -1500 J
d) -1800 J

9. A circular disc of radius R is removed from a bigger circular disc of radius 2R such that the circumferences of the discs coincide. The centre of mass of the new disc is at αR distance from the centre of the bigger disc. The value of α is

a) 1/2
b) 1/6
c) 2/3
d) 1/3

10. A 90 kg body placed at 2R distance from surface of earth experiences gravitational pull of: (take R = Radius of earth, g = 10 ms^-2)

a) 400 N
b) 100 N
c) 900 N
d) 200 N

11. Two wires are made of the same material and have the same volume. However, wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If the length of wire 1 increases by △x on applying force 1/3 newton, how much force is needed to stretch wire 2 by the same amount?

a) 2
b) 3
c) 6
d) 9

12. A capillary tube of radius R is immersed in water and water rises in it to a height H. Mass of water in the capillary tube is M. If the radius of the tube is doubled, mass of water that will rise in the capillary tube will now be

a) 2M
b) M
c) M2
d) 4M

13. The work done in increasing the radius of a soap bubble from 4 cm to 5 cm is Joule (given surface tension of soap water to be 25×10⁻³N/m)

a) 0.5657×10⁻³
b) 5.657×10⁻³
c) 56.5×10⁻³
d) 565×10⁻³

14. A particle executes simple harmonic motion with an amplitude of 4 cm. At the mean position the velocity of the particle is 10 cm/s. The distance of the particle from the mean position when its speed becomes 5 cm/s is

a) 2(√3) cm
b) 2(√5) cm
c) √5cm
d)√3cm

15. The displacement of a particle in S.H.M. is given by x=5[cosπt + sinπt] where x is in metre. The amplitude of motion of the particle is given by

a) 8 m
b) 10 m
c) 5√2m
d) 10√2m

16. A bat emits ultrasonic sound of frequency 100 kHz in air. If this sound meets a water surface, the wavelengths of the reflected and transmitted sound are (Speed of sound in air = 340 m s⁻¹and in water = 1500 m s⁻¹)

a) 3.4mm,30mm
b) 6.8 mm, 15 mm
c) 3.4 mm, 15 mm
d) 6.8 mm, 30 mm

17. The fundamental frequency of a closed organ pipe is same as the first overtone frequency of an open pipe. If the length of open pipe is 50cm, the length of closed pipe is

a) 25cm
b) 12.5cm
c) 100cm
d) 200cm

18. A long, thick straight conductor of radius R carries current I uniformly distributed in its cross-section area. The ratio of energy density of the magnetic field at distance R/2 from surface inside the conductor and outside the conductor is:

a) 1:16
b) 1:1
c) 1:4
d) 9/16

19. A particle having charge 100 times that of an electron is revolving in a circular path of radius 0.8m with one rotation per second. The magnetic field produced at the centre is

a) 10⁻⁷/μ₀
b) 10⁻¹⁷μ₀
c) 10⁻⁶μ₀
d) 10⁻¹⁵/μ₀

20. The photoelectric threshold wavelength of silver is 3250×10⁻¹⁰ The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536×10⁻¹⁰m is
(Given h=4.14×10⁶ms⁻¹eVs and c=3×10⁸ms⁻¹)

a) ≈6×10⁵ms⁻¹
b) ≈0.6×10⁶ms⁻¹
c) ≈61×10³ms⁻¹
d) ≈0.3×10⁶ms⁻¹