Answer:
The answer is 0.5 Hz
Explanation:
Its pretty easy to get the answer. One hertz (Hz) is equal to one cycle or period per second. So, just divide the period by the number of seconds.
1 period/2 secs = 1/2 Hz or 0.5 Hz
The answer would be solubility
A textbook would hit the ground first
Factors:
-Textbook weighs most
-Pillow is flat and fluffy not very aerodynamic) also is very light
-Paper airplane will glide to the ground do to its wings and will hit the ground last