Sums of Forces

According to the Laws of Physics, this is...

The motion depicted here is...

Σ\overrightarrow{F_x}=\overrightarrow{F_{net}}_{_x}=\overrightarrow{F_4}+\overrightarrow{F_2}=150N so...

When the Σ\overrightarrow{F}=0, \overrightarrow{a} is also zero.

There is negative acceleration when the Sum of Forces is Zero.

Both of these are acceptable in Physics.

This letter is Greek, and its name is...