Velocity - speed, distance and time - math lesson - By tecmath
Transcript
00:00 | Good day and welcome to the Tech Math channel , | |
00:02 | we're going to be having a look at in this | |
00:03 | video is , we're going to be looking at calculations | |
00:05 | involving speed . These are ones where we would either | |
00:08 | be working at , say , how far something was | |
00:11 | going in terms of , say kilometers per hour or | |
00:14 | MPH given , uh , time and distance or maybe | |
00:18 | working at distance calculations or time calculation . So everything | |
00:22 | involving speed , how far and how fast and that | |
00:25 | sort of thing . Now , I'm gonna assume when | |
00:27 | we're doing this , you don't know very much , | |
00:28 | okay . Uh , but we're gonna be going through | |
00:32 | this and I'll show you a few good little tricks | |
00:33 | . Now , this is my really , really bad | |
00:35 | drawing of a car and I'll draw this on here | |
00:36 | for a reason not to show you my astounding art | |
00:39 | skills , which I know , I know they are | |
00:41 | incredible . But what I'm actually looking at with this | |
00:44 | is this is the thing most people understand with speed | |
00:47 | , okay ? Because you're driving down the road and | |
00:50 | quite often you see , and quite possibly pay attention | |
00:54 | to these particular signs . Okay ? And I'll tell | |
00:58 | you how fast you should be going . Okay . | |
01:00 | Speed limit signs . Most people know this . Okay | |
01:02 | . So speed is our , okay , this is | |
01:05 | a speed we should be going . I'll even write | |
01:07 | that down there . Speed should be equal To 60 | |
01:11 | , that's 60 . What ? And most people do | |
01:13 | understand if you're in Australia , that means 60 km | |
01:19 | Per hour . Or if you're in the states , | |
01:21 | you might call this 60 mph . But straight away | |
01:26 | We have got ourselves a formula . Okay , I'm | |
01:29 | gonna rub this 68 because it's sort of a relevant | |
01:32 | place might not say that , but you're gonna see | |
01:35 | here . But what we have is we have a | |
01:39 | distance over time . Okay , The speed is equal | |
01:45 | to distance , Okay , over time , this might | |
01:50 | be MPH or something like this . So I'm gonna | |
01:53 | write our formula down here . Speed is equal to | |
01:57 | no rub their their . So when we do this | |
02:02 | , we're gonna say distance over time . Look , | |
02:11 | I'm gonna leave that car up there for the minute | |
02:13 | just so you can all bask in my , my | |
02:15 | great , my great art . But you see this | |
02:17 | will be something like a kilometers per hour or MPH | |
02:23 | or meters per second . I think of labor . | |
02:25 | The point on that one . So you should know | |
02:28 | the formula is is a really great way of remembering | |
02:30 | this particular formula . Okay , so that type of | |
02:33 | question you might get asked what this is . Say | |
02:35 | , You might say , what is the speed of | |
02:37 | an object ? What is the speed of a car | |
02:39 | ? If it goes and you'll be given a distance | |
02:42 | and you'll be given a time . So let's , | |
02:44 | let's give you one here , say we were given | |
02:46 | a distance of uh , it went , uh , | |
02:50 | let's say 120 kilometers and it did this in a | |
02:56 | time of uh , let's say five hours . It | |
03:02 | was flying along that it's not very fast at all | |
03:05 | . So how would we work out what speed ? | |
03:07 | This car slowly went down the road or we go | |
03:10 | distance Over time . Distance , which is 120 kilometers | |
03:17 | again , For this particular one is km over time | |
03:23 | . Five airlines . Okay , so 120 Divided by | |
03:31 | five is Eagle two 24 24 kilometers . Uh huh | |
03:39 | . Our . Okay . See kilometers . Uh huh | |
03:44 | . Yeah , kilometers per hour . Okay , so | |
03:46 | hopefully you're good with these . This doesn't matter if | |
03:49 | you're talking about MPH . It's the same formula . | |
03:52 | If you're talking about meters per second , it's the | |
03:54 | same sort of thing . Okay , so our units | |
03:57 | over here are going to change them . Okay . | |
04:00 | Just one thing to be careful of with this , | |
04:03 | and that is a bit later on . You want | |
04:06 | to watch these units and I'll give you a heads | |
04:08 | up when we're doing these . So that's all well | |
04:11 | and good . And that's if you want to work | |
04:12 | at speed . But say we were given the speed | |
04:13 | and were given a time and we want to work | |
04:15 | out the distance . Something interesting to say we were | |
04:17 | given a time . So we're giving a speech at | |
04:21 | a distance . We want to do it at the | |
04:23 | time . We were given a time to speed and | |
04:24 | we wanted to work at this is how we do | |
04:26 | this . We're gonna show you a little way of | |
04:29 | being able to change this formula around , and this | |
04:31 | is not involving anything divided by this at times you | |
04:35 | buy this and then moving that over there and moving | |
04:37 | this over here show you are far far simpler way | |
04:40 | of doing this . And that is through this idea | |
04:43 | . First off , you draw yourself a triangle . | |
04:48 | Okay , this is my triangle here . Isn't it | |
04:50 | beautiful . Put a T right in the middle of | |
04:52 | it , and we're gonna be using that T . | |
04:54 | Because I'm going to write this . Our formula here | |
04:56 | are speed equals distance over time . Do you see | |
05:01 | that speed is equal to distance over time ? Also | |
05:06 | look , I know it's hard to do . I | |
05:08 | am going to rub out this car . Okay . | |
05:10 | What happens if we wanted to work out ? Say | |
05:12 | , uh time ? The time calculation this would be | |
05:18 | equal to And I'm gonna put my thumb over the | |
05:20 | top of this and you're going to see that we | |
05:21 | have the distance is over . The speed . Time | |
05:25 | is equal to distance over speed , and that is | |
05:28 | true . Okay , so distance over speed . Okay | |
05:42 | , how's that for your ? Pretty good ? Say | |
05:44 | we wanted to work out in fact , what about | |
05:48 | first off ? I give you I example of this | |
05:52 | , I say we were given a distance that had | |
05:54 | been traveled , which was 1000 boils , I'm not | |
06:01 | actually sure how to abbreviate miles , we don't tend | |
06:04 | to use them over here Australia , but anyone wants | |
06:06 | to tell me , I'm not sure , I sort | |
06:07 | of feel like telling them using them before we abbreviate | |
06:09 | meters over here , but we were doing a speed | |
06:13 | . Oh uh so we were doing um It was | |
06:19 | better take a 100 10 km now , but say | |
06:23 | we were doing a speed of 60 boils , so | |
06:30 | the hour . Mhm . How long will this take | |
06:34 | ? So we would use our formula and we would | |
06:36 | say that our time is equal two . This distance | |
06:44 | , which is 1000 miles . I'm going to abbreviate | |
06:47 | . Um I'm probably going to be doing totally wrong | |
06:49 | there but Okay . Over the speed , which is | |
06:54 | 60 boils per hour . Okay , Now the answer | |
07:00 | to that , if we were to do this is | |
07:04 | is 16 .6 16.6 What you're going to see here | |
07:11 | ? That this and this cancel each other out ? | |
07:14 | So we're left with hours . Okay . And it | |
07:19 | makes sense . Okay . This is a time measure | |
07:21 | . We've got our measurement in hours . Okay . | |
07:23 | And just be careful what have we got these particular | |
07:26 | decimals involving thomas ? Doesn't mean uh you know , | |
07:29 | this is actually 0.6 of 60 minutes . So so | |
07:32 | just yeah , just , just be careful of those | |
07:34 | . Anyway , what about we now work out a | |
07:38 | distance measurements , so hopefully that's pretty good . So | |
07:43 | let somebody look at a distance measurement . So I'll | |
07:46 | get my lucky red pen and I'll go distance and | |
07:52 | this is equal to distance . I put my thumb | |
07:56 | over this here , my yellow pen and I will | |
07:59 | say that it equals their speed times time . Okay | |
08:03 | , so distance equals speed times time . Okay , | |
08:06 | speed times time . Okay , so say we were | |
08:15 | given a um speed uh what about we were doing | |
08:25 | 100 kilometers forever and we were given a time of | |
08:41 | 30 minutes and I'll chuck this in here today , | |
08:45 | a little bit confusing here to show you a little | |
08:47 | pitfall here . Now first off , what you're gonna | |
08:50 | notice is we can go this time is correct . | |
08:52 | We can't and I'll tell you why because their biggest | |
08:55 | problem with this is our units are not the same | |
08:57 | here , We've got time measurement Where they're in different | |
09:00 | units . Now we have to get these units the | |
09:03 | same before we start . So I'm gonna change this | |
09:06 | into ours , so 30 minutes is happy hours and | |
09:10 | you're gonna see that half an hour , which I'm | |
09:13 | going to write as 0.5 hours . Mhm . Okay | |
09:22 | , so our speed is equal , not working at | |
09:27 | speed , What am I doing ? A distance is | |
09:31 | equal to speed , times time speed , Which is | |
09:36 | 100 kilometers the hour , And this is times 0.5 | |
09:44 | hours trying to squash in my work there . Okay | |
09:49 | , so with this , Okay , um what are | |
09:55 | we gonna do now ? We're gonna multiply these guys | |
09:56 | out together , so 0.5 times 100 and we're going | |
09:59 | to get an answer . 2.5 times 100 is 50 | |
10:02 | 50 watts . And we're going to see that hours | |
10:05 | cancel each other out because this is dividing and this | |
10:08 | is timely at the time , so we're just going | |
10:10 | to end up with kilometers . Okay , so our | |
10:14 | distance is 50 km , so hopefully you're fairly good | |
10:19 | with these . Okay , so there's a couple of | |
10:21 | things to remember that , how to work out those | |
10:23 | distance over time type measurements , but then how to | |
10:25 | change them around and then it's just a simple matter | |
10:27 | of plugging things into the formula anyway , hopefully you | |
10:31 | understand that and hopefully it's really good . Any questions | |
10:34 | comments as usual ? Please send them through anyway . | |
10:37 | Take care of yourself . |
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