What is shake?

Explanation

**Step-by-Step Solution:**

1. **Definition of Shake**: A shake is a unit of time used in the field of physics.

2. **Value of Shake**: One shake is defined as \( 10^{-8} \) seconds. This means that a shake is a very short duration of time.

3. **Context of Usage**: The shake is primarily used in the context of nuclear reactions, particularly in neutron reactions. This is because the processes involved in these reactions occur very rapidly, making the shake a suitable unit for measuring such short time intervals.

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