Same direction, different lines
Now to the cases where two parallel forces act without being collinear. The motor car is in front of us again.
Figure to be added
As in figure 9.8, one person pushed the motor car with a force of 150 N and it did not move.
Figure to be added
But when the help of another person applying a force of 200 N was obtained, the car moved on the occasion the two of them pushed it. That happened because the resultant of the two forces they applied was enough to move the car.
How is this different from section 9.2?
Although these two forces were applied in the same direction, they are not collinear. They are parallel forces applied at different points of the motor car. One direction, but two lines of action — one person pushes high on the back of the car, the other lower down.
But the answer does not change
When two forces are applied to an object in the same direction, the resultant is the sum of the forces.
resultant force = 150 N + 200 N
resultant force = 350 N
Having two lines of action does not change the sum. The activity on the next page establishes that.