The idea that "students ' immune systems have declined due to the use of hand sanitizers " is a hypothesis.
The term hypothesis refers to an intelligent guess or idea often based which is subject to scientific investigation via experiments.
A hypothesis may be right or wrong. We can only prove a hypothesis by subjecting it to a series of rigorous experiments.
Thus Collette's idea is a hypothesis.
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This could be Hubble's law, or something related to it. I think there's a possibly Doppler RED SHIFT in the optical spectra of stars etc as observed on the earth. It seems that they are accelerating away from the earth, and that the further away they are the faster they are moving.
It seems that this has been connected to the idea of "The Big Bang" theory of the origin of the universe which seems to have superceded Professor Sir Fred Hoye's Steady State theory of the universe.
There's some Special Relativity in this lot, too.
Answer:
7 s
Explanation:
u = Initial velocity of rock = 12.2 m/s
= Angle of throw = 
x = Displacement in x direction = 25 m
Displacement in x direction is given by
Time taken to reach the ground is 7 s.
