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ESPN Relaxing with Impulse

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Video viewed in class on 12/5 corresponding to the assigned questions

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sports figures put your brain in the game just kick that ball but I did some way cooler than that I changed the balls moment sitting here on the T the balls momentum is zero that has mass but no velocity just sitting here no it has momentum it's moving it has mass and velocity how did I change a Snowman you might think that's a kick but it's not it's really an impulse in physics we describe the force that changes something's momentum with the word you know the word impulse right it's when you do something on the spur of the moment without giving it much thought like when you buy all the stuff next cash register that's called impulse Vine same thing a force that happens over a finite period of time time is what makes a force and impulse how long of force Acts so Napoleon you take a lot of hard hits out there definitely on a game-to-game basis skip Crush by someone like Derrick Thomas how do you how do you guys just bring back up I mean how do you not break every bone in your body and spending a lot of time in off-season getting physically fit and getting prepared for the pound and they were about to take during the year another way of running back and lessen the force of attack or is to relax that seems weird right I mean how good relaxing when you're about to get tackled help it seems to me if I were going to hit by Eric Thomas I want to tense up my muscles when I got tackled so why don't relax I guess it'll be like your body bends when it gets hit so it doesn't hurt write something that breaks easy and Sunday bands get more flexible  has to do with time what am I wear to jump from this diving board and land on the concrete down below what if I were to jump from up here and  land in the water we know that the watermelon had momentum When we dropped it and we know that both watermelons have the same momentum because they have the same mass and they are dropped from exactly the so why did one watermelon Splat and the other survive I think the reason I can jump from way up there and land safely in the water is because water is softer than concrete for not shorter right but the reason it really worse is time when the watermelon hit the concrete lots of momentum after it hit the concrete its momentum with zero it stopped its momentum was affected by a force the resistance of the when the watermelon hit the water and have the same amount of momentum and after it hit the water its momentum with zero it's stopped its momentum was also affected by side Force the resistance of the wall the change in momentum was exactly the same because of that we could say that both watermelons were affected by force and forces change momentum but obviously the forces affected the Watermelons a little differently the difference was that it took longer for the watermelon to stop in the water right so we can't just look at the presence of force we have to look Cat Force and time and a pulling force and time our impulse correct the differences how long it took for the momentum to change and the time it takes forced to change something's momentum is an Impulse right remember when we said when a force changes something's momentum over a finite period of it's an Impulse momentum impulse moment what are they do know about momentum is that it has both magnitude and direction to a change in direction is it change I meant the two let's go to the sports figures Blackboard  an Impulse doesn't necessarily have to stop air like a tackle often will see a running back bounce off another player changing his Direction that's an Impulse to hear we see Kaufman take a shot but doesn't stop it what it does is change his direction if his direction is changed you know his momentum is changed that's impulse at work right there what this means can we can figure out impulse in more than one dimension 1/4 for a finite period of time it can stop you or change your direction but it's always an impulse Mark Malone for the sports figures Blackboard  the polls was the same for both watermelons but the four was greater for one because the time was so small the difference in time as what smashes the watermelon or not look how long it took for watered stuff the downward momentum the same thing happens when we give momentum to an object that when we kick a football adding a lot of force over a short period of time that's an Impulse so what would happen if we give it the same amount of time people what's the same as a water well we can figure it out like this kick the football  look at the equation for impulse first time what time equals the change in momentum we get the change in momentum by subtracting the momentum after the impulse from the momentum before the impulsive we know the footballs momentum before the zero because it's not moving after Veronica kicks it we figure out the moment if I multiplying mass and velocity let's hear kick resulted in a momentum of 6 kilos mean so that's her change in momentum 6 can High Speed photography we can find how long the ronica's foot was in contact with a ball about 1007 second that's our time that we just divide the momentum by the time to get a force of 750 Newtons okay so Veronica's kick had a force of 750 Newtons now let's see what happens if we change the balls momentum with the same force over it different time will have to throw the ball  again the ball starts with the momentum of zero and when Mohammad throws it the ball has a Save-A-Lot and obviously the same man well how much thrill gives it the same momentum as Veronica's kick 6 kilos meters per second but the big difference is this when we pick her up what time during which Muhammad applied force to the ball we find that it's much slower is Hannah's moving forward with the ball for half a second we saw her ass again and get 12 News at 4 well that was way different wasn't even close I mean your forces a whopping 750 Newtons but yours is only 12 yeah but the ball with the same speed of time skip time to get the same result there's lots of ways to get an Impulse of 6 kilos meters per second a large force in the shore what time or small force in a long time call  the force they always tell you to follow through when you hit the ball because the longer you make contact with the ball the bigger the impulse and the bigger the momentum change that brings us to football pads pads are filled with soft cushy phone there's foam in this helmet foam under the shoulder pads these are hip pads and these are thigh pads off and phone is all about time what are the thing football pads do is increase the impact time when you get hit the phone compresses in that takes time just like the water the force is less because it changes your momentum more slowly look at the way an airbag Works what the airbag does is that time to the impact more time less for the principle of force x time equals change in momentum is around us every day is he what a shock absorber really does is extend the amount of time of the impact more let's Force  okay Napoleon so now we know why you're supposed to relax when you it works like this hold up your hand and hold it really stiff okay  now hold up your hand relaxing okay why they didn't hurt at all seen that when you get hit in your body relax your body gives way with the hit right and the more time it takes to change the momentum the the force white haven't you ever heard the expression roll with the punches yeah sure now it doesn't seem like you can change time of impact much by relaxing but we saw was kicking the ball and throwing the ball that every fraction of a second has a big effect on Force when you're getting hit by Derek what time is you take all you can get  okay guys so what do we learn that the chain something moment  I need a nympho an Impulse is a forest for a finite period of time in the time that it takes for momentum change determines the force alright very cool let's let's play some football so while it might seem like tightening up your muscles when you get tackled is the way to go relaxing is really the key I told you  well I like to take to pull in coffin no greater I got momentum and of course our students smart quiz Muhammad Veronica Officer Steve level of the Oakland Police Department for helping us out today on ESPN sports figures relaxing weekend running with moment you can have this back now thanks for watching go

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