Which one of the following statements about speed and velocity is correct?
- A.Speed and velocity both are vector quantities.
- B.Speed and velocity both are scalar quantities.
- C.Speed is vector quantity and velocity is scalar quantity.
- D.Speed is scalar quantity and velocity is vector quantity.
Correct answer
Explanation
The correct answer is D, Speed is scalar quantity and velocity is vector quantity. Speed tells only how fast a body moves, while velocity also tells the direction of motion, and a quantity with both magnitude and direction is a vector. Speed is distance travelled divided by time, and velocity is displacement divided by time; both are measured in metres per second. Because displacement can be zero when a runner finishes a lap where they began, the average velocity for that lap is zero even though the average speed is not. A body moving in a circle at steady speed still has a changing velocity, because its direction keeps changing. Option A is wrong because speed has no direction, so it cannot be a vector. Option B is wrong because velocity includes direction, so it is not a scalar. Option C is wrong because it swaps the two. Exam tip: scalar = distance, speed, mass, time; vector = displacement, velocity, acceleration, force.
Practice Questions
View allA recent movie titled The Man Who Knew Infinity is based on the biography of
- A.S. Ramanujan
- B.S. Chandrasekhar
- C.S. N. Bose
- D.C. V. Raman
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The 2015 film 'The Man Who Knew Infinity' tells the life of the Indian mathematician Srinivasa Ramanujan and is based on Robert Kanigel's 1991 biography of the same name.
Read the full explanation →The word 'Denisovan' is sometimes mentioned in media in reference to
- A.fossils of a kind of dinosaurs
- B.an early human species
- C.a cave system found in North-East India
- D.a geological period in the history of Indian subcontinent
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Denisovans were an archaic group of humans, close relatives of the Neanderthals, first identified in 2010 from a finger bone found in Denisova Cave in the Altai Mountains of Siberia.
Read the full explanation →Which one of the following statements best describes the role of B cells and T cells in the human body?
- A.They protect the body from environmental allergens.
- B.They alleviate the body's pain and inflammation.
- C.They act as immunosuppressants in the body.
- D.They protect the body from the diseases caused by pathogens.
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B cells and T cells are lymphocytes, the white blood cells of the adaptive immune system that recognise and fight specific bacteria, viruses and other pathogens.
Read the full explanation →Which one of the following is not used as fertilizer?
- A.Ammonium nitrate
- B.Ammonium sulphide
- C.Ammonium phosphate
- D.Ammonium sulphate
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Ammonium sulphide is an unstable, foul-smelling compound that breaks down to release ammonia and toxic hydrogen sulphide, so it is not used as a fertiliser.
Read the full explanation →The focal length of the objective lens of a telescope is 50 cm. If the magnification of the telescope is 25, then the focal length of the eye-piece is
- A.12.5 cm
- B.5 cm
- C.2 cm
- D.10 cm
Show answer
For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.
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