Question

:

Answer 1

your Y intercept is the constant of the expression, where the is no power of x

where a quadratic is written in the form
\[ax^{2} + bx + c\] where c is your constant, and c is the y intercept

Answer 2

you know that when x is 0 the constant remains

so in your question, the y intercept is when t is 0
t stands for time

so the y intercept represents the time t=0