What is the SI unit of force?
- A.Joule
- B.Newton
- C.Watt
- D.Pascal
Correct answer
Explanation
The correct answer is B, newton. One newton is the force that gives a mass of one kilogram an acceleration of one metre per second squared, which follows directly from the equation force equals mass times acceleration. Its dimensional formula is therefore M L T⁻².
Option A, the joule, is the unit of work and energy: one joule is the work done when a force of one newton moves its point of application through one metre. Option C, the watt, is the unit of power, that is the rate of doing work, and equals one joule per second. Option D, the pascal, is the unit of pressure and equals one newton per square metre. All four are derived units named after scientists, and papers often list them together to see whether you can match each with its quantity.
Read the full article: Units and Measurements: SI Units, Dimensions and Instruments
Practice Questions
View allHow many base units are there in the International System of Units (SI)?
- A.Five
- B.Six
- C.Seven
- D.Nine
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The SI system, adopted in 1960 by the General Conference on Weights and Measures, rests on seven base units: the metre, the kilogram, the second, the ampere, the kelvin, the mole and the candela.
Read the full explanation →Which one of the following is NOT a base unit of the SI system?
- A.Kelvin
- B.Mole
- C.Newton
- D.Candela
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The newton is a derived unit: it is built from the kilogram, the metre and the second, since force equals mass times acceleration, and it can be written as one kilogram metre per second squared.
Read the full explanation →The candela is the SI unit of which physical quantity?
- A.Luminous intensity
- B.Electric current
- C.Amount of substance
- D.Pressure
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The candela takes its name from the candle, which was once used as a rough standard of light, and it is one of the seven base units of the SI system.
Read the full explanation →A light year is a unit of which of the following?
- A.Time
- B.Distance
- C.Speed
- D.Brightness of a star
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A light year is the distance that light, moving at about three lakh kilometres per second, covers in one year, which works out to roughly 9.46 trillion kilometres.
Read the full explanation →The SI unit of pressure is
- A.Newton
- B.Pascal
- C.Hertz
- D.Tesla
Show answer
Pressure is force divided by area, so its unit is one newton per square metre, which is given the name pascal after Blaise Pascal.
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