What is Net Force?

As we start to explore the world of physics and motion and look at how things interact more closely, we start to see that nothing happens without affecting or being affected by something else. That idea plays nicely into something called Newton’s 1st Law, but first, let’s talk Net Forces.

Net force is what we get when we combine all of the forces acting on an object. Now, the picture below is a simplified version of the story. There are all kinds of types of forces that we’ll get into later, but for now, this works!

Net Force is a combination of all forces. Two people pushing an object together, one with 10 N of force and one with 5, will push with 15 N of force

In the picture, one person is pushing a weird rectangle thing with 10 Newtons of force. Person 2 is pushing with 5 Newtons of force. If you’ve been following this series in order, you now know 1 Newton is equal to 0.22 lbs of force.

Anyway, the combined force of their pushing is going to be 15 Newtons.

But what about when the forces are working against each other? Good question, you asked in my imagination!

Two people pushing against each other with unequal force. If one is pushing with 10 N and the other with 5 N, the net force is 5 N in the direction of the stronger push.

In this case, the box thing is being pushed with 10 N of force to the right, and only 5 to the left. Think for a moment: what will happen to the motion of the box?

Right! 10 Newtons is stronger than 5, so the person pushing with more force will overpower the other and the box will move to the right.

But because there’s resistance, Mr. Muscles over here isn’t moving the box with a full 10 Newtons of force. He’s moving it with 5. Our arrow which tells us what direction forces are being applied, called a vector, will point to the right.

Okay, okay, but what about something like tug-of-war? Is pulling any different?

No, not really. The concept remains the same. When two forces are acting against each other, you subtract the smaller from the larger. The arrow, or vector, will then point in the direction of where the object ends up moving, or in the direction the greater force is being applied.

But what if the Net Force is 0? Well, friends, that is called equilibrium.

And that’s a topic for next time!

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