We want a mile in the numerator.If you want to know the velocity of a moving object, then the right tool for the job is a velocity calculator. Or you could say there's oneġ.61th mile per kilometer. Kilometers per hour, we're going to a larger unit. Go slightly smaller amount of miles in a certain Kilometers in a certain amount of time, you're going to Or reasonably larger unit than a kilometer. Tell you, just in case you don't know, is that 1.61 Units, which are ironically not necessarily used in the UK. Imperial units, or sometimes called English And now the last thing I want toĭo, for those of us in America, we'll convert into Going to cancel out, and we're going to be left Think about it is we want hours in the denominator. In a second, so it's going to be times 3,600, thereĪre 3,600 seconds in an hour.
Well, hours, there'sģ,600 seconds in an hour. Little bit of time to think about that one. Kilometers, and then I have my seconds right over here. Is going to give you- so if you divide by 10, And the numbers, you getġ0.4 divided by 1,000. What do we get? Well, the meters cancel out. Kilometer over 1,000 meters, this is 1 over 1.
This way, how many meters are in 1 kilometer? 1 kilometer is equal To be a much smaller number of kilometers. Unit, meters, to a larger unit, kilometers. Think about it is we're going from a smaller In the numerator, we could divide by meters here. Kilometers, and we want to get rid of these meters. The units, we want to get rid of this in meters, Is 10.4 meters? Well, kilometers is a much Going 10.4 meters per second, how many kilometers And I'll give youĭo this to turn this into kilometers per second. And I'll write meters inīlue, and seconds in magenta. Write- so let me just go down here, start over. If you can rewrite this in kilometers per hour. Is his average speed, or his average rate, You is to express this speed, or this rate- and this When we drive a car, we don't see the speedometer Meters per second- meters per second is equal to my rate. Significant digits here- so let's say 10.4. So I've got 100 metersĭivided by 9.58 seconds gives me 10 point. Meters per second, which are the exact units that Left hand side, I'm left with 100 divided by 9.58. To divide the first thing by that same amount. I have to divide theĮqual to another thing, and I divide the other thingīy something, in order for them to still be equal, I have To still be true, I need to divide the leftĭivide the right side. Right side by 9.58, in order for the equality But the units cancel out,Īnd the 9.58 cancels out. Just divide the right hand side by 9.58 seconds? Because if I did that,ĭimensional analysis. I'll just have rate on the right hand side. If I were able toĭivide this right hand side by 9.58 seconds, Hand side of the equation, I have 9.58 seconds times rate. So how can we do that? Well, if you look at this right It's equal to rate times-Īnd what's the time? We do know the time. You could figure out the rate in terms ofĪnd we know the time. What you need to attempt to do is now give us our rate in It's how long it took Usainīolt to run the 100 meters. Took Usain Bolt to run the 100 meters? And I'll give you another few This equation right over here? Well, do we know the time? Do we know the time? What was the time that it Now, what else do we know? Do we know- well, we're
In the video we just did? And I'll give you a second We actually have? So do we have the distance? So what is the distance Way, let's actually think about the problem at hand. Out, and you're just left with the units of meters. The denominator and seconds up here in the numerator. Make intuitive sense that you went 20 meters. That for two seconds, then it should hopefully
Speed were 10 meters per second- just as an example. The traditional multiplication symbol can seem very confusingīecause it looks just like the variable x. Times like that, but once we start doing algebra, And you might already beįamiliar with the notion that distance is equal So we're really thinkingĪbout, in the case of this problem, average How fast was Usain Bolt going over the 100 meters. And now I'll give you a littleīit of time to think about it, and then we will solve it. The video as many times as you need to do it. Speed when he ran that 100 meters right there? And I encourage you to watch How fast was Usain Bolt going? What was his average It's exciting in any language that you might watch it. This is OK under fair use, because I'm really usingĪ question about it. Some footage here of one of the most exciting