Question

1. how much shorter is a day on the 2. what is a \time scale?\

Explanation:

1. To answer how much shorter a day is on a certain planet (the question seems incomplete as it doesn't specify which planet), one would need to know the rotational periods of Earth and the other planet and calculate the difference. For the second question, a time - scale is a system of measuring time intervals. It can be used in various fields like astronomy to measure long - term cosmic events, in geology for Earth's history, or in daily life for scheduling.
2. A time - scale is a system or scale for measuring time, often used to mark or compare the duration of events or intervals.

Answer:

1. Incomplete information to provide a numerical answer. Need to know the planet in question and its rotational period compared to Earth's (24 hours).
2. A system or scale for measuring time intervals used in various contexts such as astronomy, geology, and daily life for scheduling and event - marking.