31. The Newton’s third law is applicable when:
[A] Bodies are at rest.
[B] Bodies are in motion.
[C] Bodies are in the air.
[D] Bodies are at rest or in motion.
[D] Bodies are at rest or in motion.
Notes:
The Newton’s third law is applicable whether the bodies are at rest or in motion. It states that “To every action there is an equal and opposite reaction.”
32. In which of the following situations, the state of weightlessness can be observed?
[A] When objects fall freely under gravity.
[B] When a satellite revolves in its orbit around the earth.
[C] When bodies are at null points in outer space.
[D] All of the above
[D] All of the above
Notes:
The weight of a body is the force with which it is attracted towards the centre of earth. Weightlessness is a situation when the observed weight of the body becomes zero. Some of the situations of state of weightlessness are: 1. When objects fall freely under gravity 2. When a satellite revolves in its orbit around the earth 3. When bodies are at null points in outer space.
33. What is the value of Universal Gravitational Constant?
[A] 6.67×10-9 N–m2 kg–2
[B] 6.67×10-10 N–m2 kg–2
[C] 6.67×1011 N–m2 kg–2
[D] 6.67×10-11 N–m2 kg–2
D [6.67×10-11 N–m2 kg–2]
Notes:
The value of Universal Gravitational Constant is same throughout the universe and is equal to 6.67×10-11 Nm2 kg-2 in S.I. and 6.67×10-8 dyne cm2 g-2
34. Which of the following relations between Kinetic energy and Potential energy is true about solids?
[A] Kinetic energy = Potential energy
[B] Kinetic energy > Potential energy
[C] Kinetic energy >> Potential energy
[D] Kinetic energy < Potential energy
D [Kinetic energy < Potential energy]
Notes:
In Solids, Kinetic energy is always less than the Potential energy. For liquids, Kinetic energy > Potential energy. For Gases, Kinetic energy >> Potential energy.
35. What is the density of whole blood at STP?
[A] 3.57 × 103 kg m–3
[B] 1.06 × 103 kg m–3
[C] 5.55 × 103 kg m–3
[D] 2
B [ 1.06 × 103 kg m–3 ]
Notes:
The densities of some common fluids: 1. Whole blood: 1.06 × 103 kg m–3 2. Mercury:13.6 × 103 kg m–3 3. Ethyl alcohol: 0.86 × 103 kg m–3
36. Which of the following produces Electromagnetic waves?
[A] Charges at rest
[B] Charges in uniform motion
[C] Accelerated charges
[D] All of the above
[C] Accelerated charges
Notes:
Neither stationary charges nor charges in uniform motion (steady currents) can be sources of electromagnetic waves. The former produces only electrostatic fields, while the latter produces magnetic fields that, however, do not vary with time. As per Maxwell’s theory, accelerated charges radiate electromagnetic waves.
37. What do we call the temperature at which the liquid and the vapour states of the substance coexist?
[A] Freezing point
[B] Melting point
[C] Boiling point
[D] Normal point
C [Boiling point]
Notes:
The temperature at which the liquid and the vapour states of the substance coexist is called its boiling point.
38. Which of the following is an example of insulator?
[A] Diamond
[B] Mercury
[C] Iron
[D] Chromium
A [Diamond ]
Notes:
Diamond is an insulator whereas Mercury, Iron and Chromium are conductors.
39. Which of the following is correct?
[A] The poles of a magnet always occur in pairs
[B] Like poles attract and unlike poles repel
[C] Both a and b
[D] None of the above
[A] The poles of a magnet always occur in pairs
Notes:
The poles of a magnet always occur in pairs. Unlike poles attract and like poles repel.
40. What is the relationship between the magnetisation of a paramagnetic material and the absolute temperature?
[A] They are directly proportional to each other
[B] They are inversely proportional to each other
[C] They are independent of each other
[D] None
[B] They are inversely proportional to each other
Notes:
The magnetisation of a paramagnetic material is inversely proportional to the absolute temperature. This is known as Curie’s law.
