(a) The resultant force acting on the body = 0
$F-F\text{ }=\text{ }0$
(b) The forces tend to rotate the body between two forces about the midpoint.
Moment of forces = $F\text{ }\times \text{ }r$
$Fr$
A body is acted upon by two forces each of magnitude F, but in opposite directions. State the effect of the forces if (a)both forces act at the same point of the body. (b)the two forces act at two different points of the body at a separation r.