How Physics Can Improve Your Lift

When was the last time you were at the gym? — I didn't know this was going to be a Senate committee hearing. — Senate committ. — I mean, damn. — I was at the gym yesterday. — Yesterday? — Yes, I was. — Nice. — I was. — So, what's your regimen typically? — Uh, I try to do cardio three or four times a week because of my condition. And — you have a heart that needs that. — And then, uh, — and this is on a treadmill. — Sometimes a treadmill, sometimes a stair climber. Mhm. — Um and sometimes a bicycle and then um I try to lift weights a couple times if I can. — Is it uh dumbbells? — Yeah, dumbbells. — Uh no barbell? — No, I have shoulder problems. — So you don't do bench? — I don't do bench presses. — Okay. So if you just do dumbbells, you never need a spotter. — Well, it depends on how heavy the dumbbell is. — No, I'm saying. But if you're lifting and it's too heavy, you just drop it. — That that'll get you kicked out the gym in my gym. They don't allow it. But yeah. No. Um you don't really know. The spotter is definitely for the bar because if the bar comes down and breaks it — Yeah. You die. — There's where spotters matter. — Absolutely. — Okay. — Yeah. — And I want to describe the physics of being a spotter. — All right. You do know that those people are not our core audience. — I'm just saying. — I think we have a few. — I'm sure we do. — Okay. — But we all, whether or not you've ever been to the fitness center, right, you've heard of spotters. — Yes, of course. Yeah. Everybody knows that. — So, let me tell you how forces work if

you didn't otherwise know. — Oh, even if I did know, I still want to hear from you, — okay? Cuz I probably would re know it. — Okay. So, first of all, you can't just engage a force without pushing against something. — That makes sense. — Okay. You can't just have in the middle of nowhere. Yeah. You're pushing against friction — on the between the rubber of your souls and the sidewalk. Okay. And Earth is recoiling against your moving forward. — Yeah. — Okay, I'll accept it. Sure. — In proportion to your relative masses. Okay. — All righty. Now, that that's a big point. — This these are forces work, — right? — And this is one of Newton's laws. For every action, — equal and opposite reaction. Okay. — The word force wasn't so fully conceived at the time. So, you call them actions. Okay. That's why, for example, a flying saucers, you know, can't just move unless something gets pushed out the back. — Exactly. — They just can't send themselves into motion. — Right. — That is not real in this universe. — So when we see them hovering and then they go, — right? They could do that, but they — would leave something behind. — That's why whenever you see rockets, there's something come out the back end. — Exactly. — All right. Some combination of mass and speed — gives you momentum to go the other way. All right. So, so you take all the forces operating on an object, some will cancel out. If they're exactly opposite, they'll just cancel. — Okay? — But if somehow there's a net force, the object will accelerate — according to that force. — Okay. — Another one of Newton's laws. Force equals mass times acceleration. — Okay. — If there's a net force, you're going to have an acceleration. — Got it. — Period. — We together on that? — Well, definitely. — Okay. Does it make sense that the bigger the mass — Mhm. the less effective a force will be in its attempt to accelerate the object because this is an equation. — Right. — All right. And they have to both sides have to equal. — Exactly. — So if I only have a certain amount of force and I'm pushing a bigger and bigger object, the acceleration has to get lower and lower to compensate. — To compensate. Okay. And of course vice versa. — Of course, — if all forces are in balance, one of two things are happening. Nothing is moving, — right? or it's moving at a constant velocity. All a force knows how to do is an accelerate something. So if all the forces are balanced, it could still be moving, just not accelerating. — Accelerate. Okay, — makes sense. — Got that? — It's all good. — Are we on the same page? — We certainly are. — Okay. If all the forces balance, I don't care how high they are. — If I just add a little force that's a net force on top of everything, it's going to move. — That's right. — I push it. I can blow on it and it will move. — Okay. — Absolutely. — All right. Let's go to the gym. — All right. — A muscle man. — Yes. I — I'm here at the gym because I want to try out the forces. — For any weightlifting where you could die if you lose your grip or your ability to support it, — you want a spotter. — Yeah. — Okay. So, now the bench press is the most common example of these. — Bench press. You're flat, — right? — For those who really watch this show. For the people show, let us do a different explainer inside the explainer. This is what a bench press is. — A bench press is a horizontal plank. Often the back can go at different angles. Best look at the limiting case. It's flat — and adjacent to each side are two little holders. — Mhm. And you have a barbell across the holders, right? — Distinct from dumbbells, which are one you'd hold in each hand. Okay? Hold dumbbells. Hold them. Okay. — Barbell weights on each side. — Okay. They're pushing it up. — And I'm strong man. And I'm not just doing reps where, — right? No, you're lifting heavy weights. — Heavy weights. You can do reps. That does a different thing to your your physical — uh muscular skeletal structures than if you lift very heavy weights. If you do reps, you'll get good toning of your muscles. Very heavy weights, you actually damage your muscles and then at the end you the muscles are rebuilt to be bigger and stronger. — That's right. — That is how you do it because you're not going to be a girly man. — So, you want to build bulk, — right? — You want these are the guys who are grunting while they're lifting the weight, — right? And by the way, just so that you know, cuz you might be intimidated by them because they're grunting a bit while they're working out, but many of them poop their pants. Just a little bit, a little bit of poop. — So, if they get the bar above the two little hooks, — right, — and they can't struggle with it, they can just pull it back onto the hooks, — right? — Because the hooks are not at the limits of your reach. They're somewhere in the middle. And then you go — and then you come down to your chest, right? Here's the scenario.

— Mhm. — I got it on my chest and I'm pushing it up. It's like my third or fourth rep of some of the heaviest weights I've ever lifted. — I reach a point not high enough to get on the hooks — and I can't push it anymore and I can't and I but I want to cuz I don't want to be girly man. Okay. And so I got to do it and people are watching me. — I can't. All right. So in comes the spotter. spotter can take a single finger — and just lift it up, — right? — Why? — Cuz it's ALL YOU, MAN. YOU GOT THIS. THAT'S WHY IT'S ALL YOU. Because all the forces have balanced — in that moment. — Yes. And so now all you need is — is one little extra net force. — This little nerd just comes with his finger and he's boom. — There it is. — And he can help you lift it all. — All it takes. They get to a point where they can't push it any further. Everything is balanced in that instant, right? — Any force will lift it. Yeah. And they want to help you too. They're there to still push. So that's why a way skinnier person can spot for and if you are the spotter and the guy, you know, is uh struggling. That is when you make a deal and when they can't lift it and you go, they say, "All right, I need you. " And you say, "$20. " — Otherwise, I walk away. So this that's the physics of spotters — nice — in the gym. — Very cool. — Now they'll typically use two hands or one hand, but they actually don't need to if they're in that moment where everything is perfectly balanced. And you think you can't participate in what's going on cuz it's heavier weight than you can lift as a spotter. This person is way stronger than you. Could kick your ass any time of day, right? And to know that you can still influence the outcome of this is physics. — Very nice. You can't get away from physics no matter what you do. Even in the gym with people WHO DON'T EVEN KNOW THAT THERE'S SUCH a thing as physics. — Now, if they get the weight and it comes down to their chest and they can't get it off their chest, right, — then the spotter is useless. — Cuz the spotter has to be strong enough to actually lift the weight. Now you need like somebody who looks like the dude who's trying to lift the weight.

— You been calling for that. Call one of the where it says come people that says staff or trainer. Get one of those dudes over there. — Exactly. So that's now by the way you might ask if it's resting on his chest. Aren't all the forces in balance? — That's a good question. — Okay. — Yeah. That's a very good question. — However, — but you can't do anything about that now. — No. Here it is. They're not in balance between his muscles and the weight. They're in balance between the weight, his chest, the bench, and the earth. You can't get behind all that. — No, you can't be laying there like, "Come on, Earth. " — So, it's a bit of physics. — Physics in the workout. — Love me some physics. — Yeah, man. I love it. And if you do happen to find yourself in this problem — and there's no spotter, — what you can do is relax one arm and then the weights tip, — right? — And try to have it tip to go off to the side of your body, — right? — And then the barbell — goes to the side — and then you can roll out from under it. — Then you roll out from under. Exactly. — Yeah. Ju just as a as an emergency measure. That's one way to do that. — Right. Just make sure there's nobody off to the side that you're tipping it to. — Yeah. And moment the moment one part is touching the earth. — Yeah, you're fine. — That's picking up a lot of the weight and now it's just a pivot. — Right. — You got it. That that's all I got for you. — Here's the thing. Uh I am never going to have that problem. — I'm just saying. — All right. There been another explainer. The gym edition. — Yes. Now give us your lunch money. — All right. Let's get out of this. — Yeah, let's do it. — All right. Neil deGrasse Tyson. Keep looking up.