Well, Well, What Do
You Know?
Each of the Big Five
equations is missing one
of the kinematic quantities,
so always start by identifying
the variable you’re
not given and choosing
the equation that doesn’t
use it.When the velocity is constant, we can simplify Big Five #1 to ∆s = vt. This is just
the definition of velocity—just as Big Five #4 is the definition of acceleration—
written in a form without any fractions. It’s possible to derive the remaining
equations from these definitions alone, but for the sake of managing your time on the
SAT Physics Subject Test, it’s best to memorize all five.