When objects are moving vertically upwards or downwards, we can use the acceleration of the earth gravitational field. g = 9.81ms-1
When moving downwards acceleration is in the positive direction, it will be +9.81ms-2 (if ignoring air resistance). Oppositely, is the object is going upwards, acceleration will have a negative acceleration at -9.81ms-2.
Examples:
A ball is hit vertically upwards at 22ms-1. Calculate the height after 2.0s.
x = ?
u = 0ms-1
v = ?
a = -9.81ms-2
t = 2.0s
X = ut + ½ at²
X = 22 × 2 + ½ -9.81² x 2²
X = 24.4m
IMPORTANT - There is not horizontal component, take acceleration as a positive or negative value of g, depending on upwards or downwards motion.