Definition:Time/Unit/Hour

Definition

The hour is a derived unit of time.

\(\ds \)

\(\)

\(\ds 1\)

hour

\(\ds \)

\(=\)

\(\ds 60\)

minutes

\(\ds \)

\(=\)

\(\ds 60 \times 60\)

\(\ds = 3600\)

seconds

Symbol

The symbol for the hour is $\mathrm {hr}$.

Historical Note

The hour was formerly defined as being $\dfrac 1 {24}$ of a mean solar day.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $60$
• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $3600$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $60$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $3600$
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): hour
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): hour