Q 01/05

Which of these quantities is measured by one of the seven SI base units?

A) Force

B) Energy

C) Time

D) Speed

Answer · why

C) Time

Time. Its unit, the second, was once a set fraction of the Earth's day, but the planet's spin proved too unsteady, so since 1967 atomic clocks have de...

Q 02/05

The metric prefix "kilo" multiplies a unit by what factor?

A) 100

B) 500

C) 1,000

D) 2,000

Answer · why

C) 1,000

1,000. Computing muddied it by calling 1,024 bytes a kilobyte, so in 1998 a separate prefix, kibi, was coined to leave kilo meaning exactly a thousand...

Q 03/05

Since a six-nation agreement in 1959, which American unit of length has been defined as exactly 0.9144 metres?

A) The foot

B) The yard

C) The fathom

D) The rod

Answer · why

B) The yard

The yard. English-speaking nations had slightly different yards, so to agree on one value the American yard was shortened and the British one lengthen...

Q 04/05

A popular myth says the United States and which two other countries are the last holdouts against the metric system?

A) Jamaica and Belize

B) Liberia and Myanmar

C) Samoa and Tonga

D) Yemen and Bhutan

Answer · why

B) Liberia and Myanmar

Liberia and Myanmar. NIST calls it a myth spread by an old CIA Factbook list: every country has adopted the SI, and even US feet and inches are offici...

Q 05/05

The 1795 law that defined the metre and gram also introduced which unit of currency?

A) The livre

B) The louis

C) The franc

D) The écu

Answer · why

C) The franc

The franc. The same reform swept away royal money too: the old livre was exchanged for the new currency at 81 livres to 80 francs.