The airtime is 9.8
the velocity is 0
The act of using senses or tools to gather information is called "observation." In scientific method, it is very essential to have this one. Through observation, we are able to get what we wanted to get using our senses and other tools. This process is very tedious if the field that you are studying is quite complicated. Hope this Helps! PLEASE PUT BRAINLIEST!
Answer:

Explanation:
We know that there is a relation between the speed of light ,frequency and wavelength.This relation can be given as
where v is speed of light
is frequency of light
is wavelength of light
In first case we have given λ=655 nm
so using formula 

Hz
In second case we have wavelength 515 nm so by using above formula


In third case we have wavelength 475 nm
so 

Answer:
t = 2.6 billion years
Explanation:
If potassium becomes 25% of its initial value
so we can say it becomes half two times
as we know that 25% means it is 1/4 times of initial value
so we will have

here we know that





t = 2.6 billion years