## Wednesday, April 24, 2019 # WBCS Previous Years MCQs on General Science (Physics) P7

61. An iron ball and a wooden ball of the same mass are released from a height h in air. Neglecting viscous drag of air
(A) There is an equal probability for the wooden and iron ball to hit the ground earlier.
(B) Both will reach the ground at the same time.
(C) The iron ball will hit the ground earlier.
(D) The wooden ball will hit the ground earlier
Correct Answer: [B] Both will reach the ground at the same time..

62. When the angle of incidence is equal to the critical angle for the media, the angle of refraction is
(A) 45°
(B) 90°
(C) 0°
(D) Angle of incidence

63. Greenhouse effect causes
(A) lowering in temp. of the earth.
(B) continuous snowing on the earth.
(C) rise in temperature of the earth.
(D) continuous rainfall
Correct Answer: [C] rise in temperature of the earth..

64. Two ends of a tube are closed by corks so that the tube become airtight. The pressure of air inside the closed tube is
(A) Equal to the atmospheric pressure.
(B) Dependent on the length of the tube.
(C) Very small.
(D) Slightly less than the atmospheric pressure
Correct Answer: [A] Equal to the atmospheric pressure..

65. The ratio of the velocity of a body to the velocity of sound is called
(A) Natural number
(B) Mach number
(C) Magic number
(D) Laplace number

66. The period of rotation of an artificial earth satellite
(A) Is inversely proportional to its mass
(B) 24 hours
(C) Depends on its distance from the earth's surface
(D) Is proportional to its distance from the earth's center
Correct Answer: [C] Depends on its distance from the earth's surface.

67. Mass of a body is defined by the following quantity
(A) Applied force / acceleration
(B) Applied force / increase in momentum
(C) Velocity / acceleration
(D) Applied force / velocity
Correct Answer: [A] Applied force / acceleration.

68. A man presses the earth least when he is
(A) Running
(B) Lying flat
(C) Standing
(D) Sitting

69. Optical fiber works on the
(A) Scattering
(B) Reflection
(C) Principle of Refraction
(D) Total Internal Reflection
Correct Answer: [D] Total Internal Reflection.

70. Two bales at the same temperature collide. What is conserved?
(A) Linear momentum
(B) Kinetic energy
(C) Temperature
(D) Velocity