Question

net force = forces going in the same direction going in opposite directions equal and opposite calculation directions: calculate the net forces acting on the objects described below. circle the number of any problem that results in no motion.

Explanation:

Step1: Forces in same direction

When forces act in the same direction, the net - force is the sum of the forces. Let the two forces be $F_1$ and $F_2$. The net - force $F_{net}=F_1 + F_2$.

Step2: Forces in opposite directions

When forces act in opposite directions, the net - force is the difference between the magnitudes of the forces. Let the larger force be $F_{1}$ and the smaller force be $F_{2}$. The net - force $F_{net}=\vert F_1 - F_2\vert$.

Step3: Equal and opposite forces

When forces are equal and opposite, $F_1 = F_2$. The net - force $F_{net}=F_1 - F_2=0$. This results in no motion.

Answer:

Forces going in the same direction: $F_{net}=F_1 + F_2$; Forces going in opposite directions: $F_{net}=\vert F_1 - F_2\vert$; Forces equal and opposite: $F_{net} = 0$