One horsepower is approximately equal to how many watts?
- A.500 watts
- B.746 watts
- C.1,000 watts
- D.1,200 watts
Correct answer
Explanation
The correct answer is B, 746 watts. The horsepower is an older practical unit of power that survives in the rating of engines, pumps and motors, and it equals about 746 watts. The watt itself is the SI unit of power and means one joule of work done in one second.
Option A, 500 watts, and Option D, 1,200 watts, correspond to no standard unit. Option C, 1,000 watts, is one kilowatt, which is a different and very common unit: the electricity used at home is billed in kilowatt hours, popularly called units, where one kilowatt hour is the energy used by a one kilowatt appliance running for one hour. Keep the two apart, since a question often offers the kilowatt as a distractor for horsepower.
Read the full article: Units and Measurements: SI Units, Dimensions and Instruments
Practice Questions
View allWhat is the SI unit of force?
- A.Joule
- B.Newton
- C.Watt
- D.Pascal
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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.
Read the full explanation →How 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.
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