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,

Ball bearings are used in bicycles, cars, etc., because

(a)

the actual area of contact between the wheel and axle is increased

(b)

the effective area of contact between the wheel and axle is increased

(c)

the effective area of contact between the wheel and axle is reduced

(d)

None of the above statements is correct

Correct Answer

(c)

Explanation

The roundness of the bearings creates less contact between the bearing that is trying to move objects and the object being moved. A reduction in contact area means less friction.

Microtheme: PhysicsXGeneral —
25 questions asked in Prelims in the past.

  1. [2023] Consider the following actions:
    1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
    2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive.
    3. Detection of the tilt of the smart phone which results in the rotation of display between portrait and landscape mode
    In how many of the above actions is the function of accelerometer required?

    • (a) Only one
    • (b) Only two
    • (c) All three
    • (d) None
    Correct Answer: (C) All three
  2. [2022] Which one of the following statements best reflects the idea behind the “Fractional Orbital Bombardment System” often talked about in media?

    • (a) A hypersonic missile is launched into space to counter the asteroid approaching the Earth and explode it in space.
    • (b) A spacecraft lands on another planet after making several orbital motions.
    • (c) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
    • (d) A spacecraft moves along a comet with the same speed and places a probe on its surface.
    Correct Answer: (C) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
  3. [2021] In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
    1. Area of the hole in the lid
    2. Temperature of the flame
    3. Weight of the lid
    Select the correct answer
    using the code given below.

    • (a) 1 and 2 only
    • (b) 2 and 3 only
    • (c) 1 and 3 only
    • (d) 1, 2 and 3
    Correct Answer: (C) 1 and 3 only
  4. [2017] What is the purpose of ‘evolved Laser Interferometer Space Antenna (ELISA)’ project?

    • (a) To detect neutrinos
    • (b) To detect gravitational waves
    • (c) To detect the effectiveness of missile defence system
    • (d) To study the effect of solar flares on our communication systems
    Correct Answer: (B) To detect gravitational waves
  5. [2017] The terms `Event Horizon’, ‘Singularity’, `String Theory’ and `Standard
    Model’ are sometimes seen in the news in the context of

    • (a) Observation and understanding of the Universe
    • (b) Study of the solar and the lunar eclipses
    • (c) Placing satellites in the orbit of the Earth
    • (d) Origin and evolution of living organisms on the Earth
    Correct Answer: (A) Observation and understanding of the Universe
  6. [2015] In the context of modern scientific research, consider the following statements about ‘IceCube’,
    a particle detector located at South Pole, which was recently in the news :
    (1) It is he world’s largest neutrino detector, encompassing a cubic kilometer of ice.
    (2) It is a powerful telescope to search for dark matter.
    (3) It is buried deep in the ice.
    Which of the statements given above is/are correct?

    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 1 and 3 only
    • (d) 1, 2 and 3
    Correct Answer: (D) 1, 2 and 3
  7. [2013] The efforts to detect the existence of Higgs boson particle have become frequent news in the
    recent past. What is/are the importance/importances of discovering this particle?
    (1). It will enable us to under-stand as to why elementary particles have mass.
    (2). It will enable us in the near future to develop the technology of transferring matter from
    one point to another without traversing the physical space between them.
    (3). It will enable us to create better fuels for nuclear fission.
    Select the correct answer using the codes given below.

    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 1 and 3 only
    • (d) 1, 2 and 3
    Correct Answer: (A) 1 only
  8. [2013] The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?

    • (a) Gravity is the strongest of the four
    • (b) Eletromagnetism ats only on particles with an electric charge
    • (c) Weak nuclear force causes radioactivity
    • (d) Strong nuclear force holds protons and neutrons inside the nucleus of an atom
    Correct Answer: (A) Gravity is the strongest of the four
  9. [2013] Ball bearings are used in bicycles, cars, etc., because

    • (a) the actual area of contact between the wheel and axle is increased
    • (b) the effective area of contact between the wheel and axle is increased
    • (c) the effective area of contact between the wheel and axle is reduced
    • (d) None of the above statements is correct
    Correct Answer: (C) the effective area of contact between the wheel and axle is reduced
  10. [2012] Consider the following statements: If there were no phenomenon of capillarity 1. it would be difficult to use a kerosene lamp 2. one would not be able to use a straw to consume a soft drink 3. the blotting paper would paper would fail to function 4. the big trees that we see around would not have grown on the earth Which of the following statements given above are correct?

    • (a) 1, 2 and 3 only
    • (b) 1, 3 and 4 only
    • (c) 2 and 4 only
    • (d) 1, 2, 3 and 4
    Correct Answer: (B) 1, 3 and 4 only
  11. [2012] Which of the following is/are cited by the scientists as evidence/evidences for the continued expansion of the universe? 1. Detection of microwaves in space 2. Observation of redshift phenomenon in space 3. Movement of asteroids in space 4. Occurrence of supernova explosions in space

    • (a) 1 and 2
    • (b) 2 only
    • (c) 1, 3 and 4
    • (d) None of the above can be cited as evidence
    Correct Answer: (A) 1 and 2
  12. [2012] Electrically charged particles from space travelling at speeds of several hundred km/sec can severely harm living beings if they reach the surface of the Earth. What prevents them from reaching the surface of the Earth?

    • (a) The Earth’s magnetic field diverts them towards its poles
    • (b) Ozone layer around the Earth reflects them back to outer space
    • (c) Moisture in the upper layers of atmosphere prevents them from reaching the surface of the Earth
    • (d) None of the statements (a), (b) and (c) given above is correct
    Correct Answer: (A) The Earth’s magnetic field diverts them towards its poles
  13. [2012] A team of scientists at Brookhaven National Laboratory including those from India created the heaviest antimatter (anti-helium nucleus). What is/are the implication/ implications of the creation of antimatter? 1. It will make mineral prospecting and oil exploration easier and cheaper. 2. It will help probe the possibility of the existence of stars and galaxies made of antimatter. 3. It will help understand the evolution of the universe.

    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 3 only
    • (d) 1, 2 and 3
    Correct Answer: (B) 2 and 3 only
  14. [2012] What is the role of ultraviolet (UV) radiation in the water purification systems? 1. It inactivates/kills the harmful microorganisms in water. 2. It removes all the undesirable odours from the water. 3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water.

    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 1 and 3 Only
    • (d) 1, 2 and 3
    Correct Answer: (A) 1 only
  15. [2011] An artificial satellite orbiting around the Earth does not fall down. This is so because the attraction of Earth

    • (a) does not exist at such a distance.
    • (b) is neutralized by the attraction of the moon.
    • (c) provides the necessary speed for its steady motion.
    • (d) provides the necessary acceleration for its motion.
    Correct Answer: (D) provides the necessary acceleration for its motion.
  16. [2011] The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?

    • (a) Ice is a bad conductor of heat.
    • (b) Since the surface of the lake is at the same temperature as the air, no heat is lost.
    • (c) The density of water is maximum at 4°c.
    • (d) None of the statements (a), (b) and (c) given is correct.
    Correct Answer: (C) The density of water is maximum at 4°c.
  17. [2010] What is the principle by which a cooling system(Radiator) in a motor car works:

    • (a) Conduction only
    • (b) Convection
    • (c) Radiation only
    • (d) Both conduction and radiation
    Correct Answer: (B) Convection
  18. [2010] India-based Neutrino Observatory is included by the Planning Commission as a mega science project under the 11th five-Year Plan. In this context, consider the following statements:
    1. Neutrinos are chargeless elementary particles that travel close to the speed of light.
    2. Neutrinos are created in nuclear reactions of beta decay.
    3. Neutrinos have a negligible, but nonzero mass.
    4. Trillions of Neutrinos pass through human body every second.
    Which of the statements given above are correct ?

    • (a) 1 and 3 only
    • (b) 1,2 and 3
    • (c) 2,3 and 4
    • (d) 1,2,3 and 4
    Correct Answer: (D) 1,2,3 and 4
  19. [2009] In the year 2008, which one of the following conducted a complex scientific experiment in which sub-atomic particles were accelerated to nearly the speed of light ?

    • (a) European Space Agency
    • (b) European Organization for Nuclear Research
    • (c) International Atomic Energy Agency
    • (d) National Aeronautics and Space administration
    Correct Answer: (B) European Organization for Nuclear Research
  20. [2009] Which one of the following types of waves are used in a night vision apparatus ?

    • (a) Radio waves
    • (b) Microwaves
    • (c) Infra-red waves
    • (d) None of the above
    Correct Answer: (C) Infra-red waves
  21. [2009] In a dry cell (battery), which of the following are used as electrolytes ?

    • (a) Ammonium chloride and Zinc chloride
    • (b) Sodium chloride and Calcium chloride
    • (c) Magnesium chloride and Zinc chloride
    • (d) Ammonium chloride and Calcium chloride
    Correct Answer: (A) Ammonium chloride and Zinc chloride
  22. [2008] Consider the following statements:
    1. A widely used musical scale called diatonic scale has seven frequencies.
    2. The frequency of the note Sā is 256 Hz and that of Nī is 512 Hz.

    • (a) 1 only
    • (b) 2 only
    • (c) Both 1 and 2
    • (d) Neither 1 nor 2
    Correct Answer: (A) 1 only
  23. [2008] Which one of the following laser types is used in a laser printer?

    • (a) Dye laser
    • (b) Gas laser
    • (c) Semiconductor laser
    • (d) Excimer laser
    Correct Answer: (C) Semiconductor laser
  24. [2008] Assertion (A): Radio waves bend in a magnetic field.
    Reason (R): Radio waves are electromagnetic in nature.

    • (a) Both A and R are individually true and R is the correct explanation of A
    • (b) Both A and R are individually true and R is not the correct explanation of A
    • (c) A is true but R is false
    • (d) A is false but R is true
    Correct Answer: (A) Both A and R are individually true and R is the correct explanation of A
  25. [2003] An oil tanker is partially filled with oil and moves forward on a level road with uniform acceleration. The free surface of oil then:

    • (a) Remains horizontal
    • (b) Inclined to the horizontal with smaller depth at the rear end
    • (c) Inclined to the horizontal with larger depth at the rear end
    • (d) Assumes parabolic curve
    Correct Answer: (C) Inclined to the horizontal with larger depth at the rear end