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okay this is homework help with ACC for that includes problem number 26 on page 69 on page 82 number 88 and 90 and then I'm page 85 number so let's don't forget to copy down the problems so let's see what this one's about  about a skateboarder skateboarder is moving at a constant velocity of 1.75 m per second when she starts up an incline that causes her to slow down with a constant acceleration of if .20 meters per second squared how much time passes from when she begins to slow down until she begins to move back down the incline so maybe pause this right here take a minute and copy down the problem number 26 okay let's get going on so let's see what we can identify first of all I know V initial that's that 1.75 meters per second that he was moving to start with nowhere acceleration it's a negative acceleration so some people call that deceleration mean slowing down means the velocity is positive the acceleration is negative there an opposite directions so that means slowing down is what this acceleration does and what else do we know when she begins to move back down the incline well that's one her final velocity is going to be zero  and then she'll start coming back down cuz they're coming the other way with a negative velocity okay so let's see here let's see how approach this I've got d a v i a n f i want to fight okay T is VF - be over at the information here you'll get a negative quantity up top because VF is 0 subtract 1.75 and then divided by a negative for the negative cancel page 82 number 88 okay right here dragster starting from rest  accelerates at 49 m per second each second how fast is it going when it is traveled 300 25 alright so this one's going to be a little different it looks like we're not using  we got a distant thing and there's no distance in that one equation I've been using so it looks like we're going to be going to a different equation here so let's take a minute here copy down the problem and let's get the ceiling is started with this one  so let's see what we have we have a dragster that starting from rest so  this is Page 82 number 88  Sylvie initial is 0 meters per second and what else do we know accelerates 49 m per second square cm organizing how fast is it going what's its we want to find final speed all this at last how fast is it going when it is traveled a distance of 325 M and I want to find  the app so here's what I've got I've got  GI the app is what I want fine and I've got AMD to do that so let's go here  might be right here there's an equation and involved via and D it allows me to find VIA there's Square things in here so this is going to be a little different than what we done before so let's see what we can do vs squared equal VI squared + 280 so we'll start using that right now I squared so that zero week eliminate that right from the equation 0 we don't have to worry about putting in zero so you can stop putting in zeros but from the equation variable or like I do put a little arrow through it that means bye bye so to 82 * 49 m per second squared times 300 25 M we're going to get meters squared per second squared is our unit when we do this and that's okay because we're going to take a square root later to saw how far to get rid of the square so they'll know what you're going to do is you'll get the answer to this VF squared equals whatever you get when you do that it'll be meters squared per second squared and then what you're going to have to do is take the square root of both sides and then you'll know what VF is in meters per second so this one has a square root that's involved with the solving this one okay let's go onto number 9 0 number 90 what is that don't forget to copy it down  number 90 of Haley on a Nabi a race car can be slowed with a constant acceleration of -11 m per second squared so we're on number 90 here if the car is going 55M how many meters will it travel before it stops and then how many meters will it take to stop a car going twice as fast so number nine  start to organize myself and this has Parts A&B so after you copy down the problem start with a so let's see with a constant acceleration of -11 m per second squared we want to know if a art is going so speed is 55 m per second and we want it to stop so it's final speed is 0 meters per second how many meters will it travel before it stops so we want to know D and what we've got is VF VI and a sew in where to do this one's going to be that same equation that involves a DVI and VGA DVI I want to say that want this Avia squared equals we wanted to say d equals so we move around the equation a little bit so we have VF squared equals VI squared plus 2 ad and I want to get the D alone so what I'm going to do is first I'm going rid of this by subtracting it to the other side VF squared minus B squared equals to A D now I'm going to divide both sides by two way eliminated over here and so now the equation becomes D equals VF squared minus B squared over 2A add subtracted VI Square to bring it to the other side and then I divided by 2A to remove that from the D okay so let's get this onto our solution VF word minus B squared over 2A squared minus B squared + what we got here via Square that's going to be 0 so we can just eliminate that you're going to square and then turn it negative  and then your a double the acceleration that's also negative you'll have a negative over a negative square VI first and then apply the negative this negative doesn't get canceled play the squared so it would have to be inside of a parentheses in order for it to get cancelled by the square it's not so you square it first and then you turn it negative then you'll have a negative on the bottom because 2 * -11 + -22 negative over and will give you a positive answer what's going to be what exactly the same way the acceleration is -11 m per second squared but this time we're saying we're going starting twice as fast so 110 M4 second is our initial speed our final is zero  and we want to find D again B squared minus B squared all over 2A so again same thing vf-20 so Square VI and then divided by two times hey in the negative she canceled once again okay on to the next question which is number one on page 85 page 85  now these are probably yeah this is a multiple choice question but want to show work so number 1 A ball rolls down a hill with a constant acceleration of a one and two are both involving this information of two is the second each second the ball starts at rest and travels for 4 seconds before it stops how far did the ball travel before it stopped so number one copy down the question can you pause it then okay let's get started acceleration is 2 m your second squared so we know a 2.0 meters per second each second we know it starts from rest we also know it travels for 4 seconds time is 4 seconds and we want to know how far did the ball stop so this is different we don't have the like we did before but we have another equation right here where involved in this equation is DVI and a we have here. ALDIs ad equals I'm going to go ahead and use it it's vit plus one half a t squared so we can eliminate that and then it's one half times the acceleration 2.0 meters per second squared and then 4.0 seconds squared you've got to do this first to get 16 seconds squared you got a square that 4.0 seconds and after you square 4.0 seconds the second squared will cancel with this one and you'll have meters so Square it x 2 / 1/2 that's really X so that's not going to change anything last one is number 2 what was the ball's velocity just before it stopped so in case we want to know if BF is equal to so how can we find VF well we've got viant so I'm going to go back VI Plus at that comes from the main equation that's a rearrangement of VF - VI over tea gives us acceleration so if I rearrange that I can solve for VF and let the I know it VI is this is going to be eliminated I know what is plug that and I know so this one should be easily soft okay good luck

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