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Net Force- Resultant Force 15,609 views

Teacher/Instructor Matt Jones
Matt Jones

M.Ed., George Washington University
Dept. chair at a high school

Matt is currently the department chair at a high school in San Francisco. In his spare time, Matt enjoys spending time outdoors with his wife and two kids.

Net force, also known as resultant force, is a vector quantity produced when two or more forces act upon one object. The concept of net force is the same as the mathematical concept of vector addition.

Let's talk about net force. This is also sometimes called resultant force, those two words are used interchangenly and basically what this is, is the vector that's produced when 2 or more forces act together. Remember anything that has distance and magnitude we can depict as a vector. So let's look at a couple of examples or how you can calculate a net force on an object okay. Let's take for example a helicopter, you may notice when helicopters go up and down they are completely vertical right?

But when they want to go forward they need to actually tilt, that's to create this thrust where they're pushing air in that direction which is causing a force in that direction. I'm going to call that f1 okay but how come that a helicopter that's tilted in this direction isn't going up in that direction? Well that's because there's a second force acting on that helicopter okay and that's the force of gravity. I'm going to call that f2, okay. So what's the overall force going to be on this helicopter? Well I have to add my 2 vectors together and I can do that easily by just taking this one and pointing it head to tail to the first one. So if I put my f2 right here I can see that my resultant vector which we'll call fa is causing it to move in a horizontal way to the earth.

Okay, so just adding vectors that helps us figure out the true vector okay. Let's say I'm playing golf another example we might see I'm going to tee off from right here and there's my hole and I want to aim right for that whole okay and I'm going to hit a shot that goes right about there okay. Now if that was my only force acting on that ball that would be a pretty good shot right. But let's say there's a wind and let's say that wind is blowing in this direction okay. So f1 is the force applied to my golf club on the ball, f2 is the wind okay.

That is going to push the ball in this direction, okay so I put f2 right there and I add these two vectors together and I actually get something that looks like that f actual okay and now I'm off in the rough alright that's not a good shot because I didn't factor in what the wind was going to do to my ball the force of the wind on my ball has actually made the actual vector far off its center. So these are some of the ways we can add vectors and see how forces interact together to create actual true vectors.