To find the net force in the system, we can represent the forces acting on the cue ball and the four ball.
- The cue ball is moving to the left with a force of 70 N, which we can represent as +70 N.
- The four ball is moving to the right with a force of 50 N, which we can represent as -50 N (since we assign negative values to forces moving to the right).
Now, we can calculate the net force:
\[ \text{Net Force} = (+70 \text{ N}) + (-50 \text{ N}) = 70 \text{ N} - 50 \text{ N} = 20 \text{ N} \]
Thus, the net force of the system is 20 N. The correct response is:
- 20 N