Acceleration of free fall
All bodies falling freely under the force of gravity
do so with uniform acceleration if air resistance is
negligible (i.e. the ‘steps’ in the tape chart from the
practical work should all be equal).
This acceleration, called the acceleration of free fall,
is denoted by the italic letter g. Its value varies slightly
over the Earth but is constant in each place; in India
for example, it is about 9.8 m/s2 or near enough 10 m/s2.
The velocity of a free-falling body therefore increases
by 10 m/s every second. A ball shot straight upwards
with a velocity of 30 m/s decelerates by 10 m/s every
second and reaches its highest point after 3 s.
In calculations using the equations of motion, g
replaces a. It is given a positive sign for falling bodies