Net Force Discussion - Simplified Golf Physics

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Hi, in this GolfSmart Insight, I'm going to help you understand the forces as

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they apply

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in the golf swing.

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I know that there's a lot of confusion out there about what the forces are, how

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you can

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see them or if you can see them, and the general patterns.

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So in this video, I'm going to hopefully clarify some of those forces,

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especially as they relate

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to the in-plane movement, sometimes referred to as alpha.

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All right, before we look at how it relates to the golf swing, I've got this

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simple little

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drawing to help you understand the net force, because I think it's often

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confused for what

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a golfer is trying to do versus what is actually happening.

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Okay, so in this scenario, I've got a cliff, right, and then there's a weight

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hanging

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around a pulley being held by this gentleman here.

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Now that pulley is not a string, it's a cable, and that's going to be important

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for this third

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situation.

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Okay, now I've got the weight on a cable attached to the guy.

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There's a couple different things that could happen.

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Scenario one, he's kind of lowering it down slowly.

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Scenario two, he's backing up and he's actually pulling it upward.

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And then scenario three, because it's a cable, he's actually pushing it down,

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so he's having

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it fall faster than gravity.

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Okay, in the first scenario, actually the second scenario is probably easy, so

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let's

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start with that.

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So in the second scenario, right here, he's got the cable moving up this way.

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He is clearly pulling on the cable back towards him like this.

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That's where the net force would be going, and it would be greater than

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whatever the

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weight is with gravity.

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On this second example, we've got the weight going down, so he's slowly letting

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it down,

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so his hands and everything would be moving this way, but because the weight is

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going

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down slower than gravity, the net force is back towards him.

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It's going to be in the same direction as him pulling up, just to a lesser

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degree or

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a lesser magnitude.

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It's only an example three, where if he was to accelerate this down greater

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than just

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what gravity would be doing, that he would actually have the force and his hand

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direction

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going out towards the pulley like so.

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Now we'll talk about where this relates to the golf swing, but the common thing

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I hear

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is, okay, if we want the forces coming back in towards you, that you need to be

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really

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pulling up on the handle.

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We'll understand that if you create a ton of club at speed, and this weight is

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pulling

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away from you, or the golf club is swinging away from you, you're going to have

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a really

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high force pulling in towards you, even though your arms are extending and kind

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of letting

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that weight kind of pull your arms out, so that's an important thing to

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understand that

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the net force is a relationship of the physics happening to you or by you, not

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necessarily

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what you're trying to do and what you're feeling.

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Now let's take that rope on a string analogy and apply it to the golf swing,

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and let's

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specifically look at going normal down to the bottom.

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So pulling up on the handle and having the force going more up towards you.

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The orange dots that I have drawn represent roughly where the center of mass

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would be,

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so just behind the shaft in the direction of a club head kind of like this.

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Again, this is incredibly rough, but we don't have to get too specific to be

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able to see

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this general pattern.

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If we take a look at these dots, and if we imagine just the vertical change, or

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just the

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change towards the ground kind of like this, you can see as you get down here

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towards

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the bottom, the vertical change between the dots gets smaller and smaller.

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That means that the center of mass is not accelerating down towards the ground,

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because

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the if it was, then the space between these dots would get bigger and bigger.

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So since the distance between the dots is getting slightly smaller, that means

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that the

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force would be working up away from the ground.

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So when we get down here, where the swing, where the club has a flatish path,

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it was

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moving very vertically through here, and then it has a flatish path.

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That means somewhere around here, which ends up being roughly when those hands

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are in front

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of the thigh, it starts to flatten out, and therefore the force would be

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working away from

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the ground from, let's say, the frame just before this, all the way down

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through and

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past the impact.

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So you can see that unless you had an angle of attack somewhere around 90

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degrees, you're

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probably going to have the net force working away from the ground or towards

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you.

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What really matters is how you apply that force away from the ground, whether

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you do

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it more from your body, whether you do it more by pulling and bending your arms

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.

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But as you've seen, you don't necessarily have to feel like you pull your hands

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in closer

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to your body in order to get the proper net force pattern.

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The other instruction that I commonly hear is down at the bottom, you want to

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be pulling

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not only up, but you want to be pulling in.

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So this is a little bit trickier to see.

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The easiest way to see this is actually from an overhead cam.

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But think of it in the same light as what we did from the face-on.

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We can see that at this phase in the downswing, the center of mass is having

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some clear movement

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out towards the golf ball.

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Now remember, if it slows down its movement out towards the golf ball or it

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changes direction

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in the center of mass starts moving away from the golf ball, that means that

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there was

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a net force away from the golf ball.

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So down here at the bottom where you can see that the path of the club starts

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working

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back up and in, that means that well before then, there was a net force that is

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working

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away from the golf ball.

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So you can see that in order to make a swing where you didn't have the net

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forces working

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back up and in or away from the ground and away from the golf ball, it would be

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very

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challenging.

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In fact, it would not look very much like a golf swing at all.

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The most important part is how you create these forces, not necessarily what

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the forces

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actually are.

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There's still a lot of stuff that we can learn from investigating these net

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forces.

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But the overall patterns kind of make sense with the general movement patterns.

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If you're not sure what the general movement patterns are or therefore what the

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arm should

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be doing in the backswing or transition or the release, either subscribe to our

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YouTube

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channel, that way you can get updates as soon as we post them online.

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Or if you want to get into the real nitty gritty, head over to golfsmartacademy

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.com, sign up

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for a free membership, and then you can take a look at the concept videos and

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the drill

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videos to help you understand all the details as far as what the body should be

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doing during

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the different phases of the swing and how to recognize the feedback as to if

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you're actually

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doing it or not.