Understanding Earth's Rotation and Timekeeping

How much longer does a day get on average every 100 years due to Earth's slowing rotation?

• Ten milliseconds

• Five milliseconds

• One second

• Two milliseconds

What was the original definition of a second based on?

• Atomic clocks

• Ephemeris second

• 1/86,400 of a solar day

• Newton's laws of motion

In which year was the SI second redefined based on atomic clocks?

• 1820

• 1975

• 1967

• 1960

Why do we not add leap seconds on a precise yearly schedule?

• Earth's rotation has irregularities due to factors like earthquakes

• Leap seconds are added every decade

• Leap seconds are unnecessary

• Earth's rotation is perfectly regular

What causes the current frequency of leap seconds?

• The rapid acceleration of Earth's rotation

• The alignment of the solar system

• A preexisting difference in the size of an SI second and 1/86,400 of a day

• The stability of atomic clocks