
Jeffrey C. answered 01/31/24
PhD in Physics with 10+ years of teaching experience
Hello. Lets see if I can help you.
The function y(t) = e-t/T
We want to evaluate the function at t = 4.
y(4) = e-4/T
We are also told that T (the time constant) is equal to 4 s-1. So T = 4.
we can now rewrite the function evaluated at t = 4 as,
y(4) = e-4/4 = e-1 = 1/e
the symbol 'e' is known as Euler's number and is equal to 2.71828 when we round it off to 5 decimal places. This is a similar idea to the number Pi or π.
So y(4) = 1/e ≈ 1/2.71828 ≈ 0.367879
Hope this helps!