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In the last video, we figured out the absolute minimum

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speed in order to stay on the circular path right over here especially near the top

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was 27.6 km/h

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What I want to do in this video is

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I just clipped out the parts where he's actually on the loop de loop

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and I want to figure out his average [speed]

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So I'm going to use the video editor right here

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to time how long it takes to complete the loop de loop

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And then we can use that and we know about the circumference of this loop de loop

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and we're going to assume that it is perfectly circular for our purpose

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although it looks like it's a little bit egg-shaped in reality or elliptical

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For our calculation, we're going to assume that it's perfectly circular

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I'll leave it to you to think about how it would change

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if you had an elliptical shape like this

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So anyway, let's watch the video again

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Remember this is from fifth gear which shows on Channel 5 in United Kingdom

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So there you go

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Let's watch it again. It's fun to watch. There you go

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And right over here, we have a little timer for my video editor

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And this right over here is in seconds and I was corrected on a earlier video

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This right over here is not in hundredth of seconds. This is in frames

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And there's 30 frames per second

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So it starts at 0 seconds 0 frames

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and then when we play it, it goes to 2 seconds and 14 frames

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There's 30 frames per second

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So it's 2 and 14/30 of a second. It's how long it takes the car to do the loop

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So 1 second, and then 2 seconds, 2 and 14/30. So almost 2.5 second

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So let's write that down

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So the time required to do the loop de loop is roughly 2 and 14/30 seconds

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And what is the distance that it travels?

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If we assume that this thing is circular although it looks like it's a little bit egg-shaped

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if we assume that it is circular

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then the distance traveled is the circumference of the circular loop de loop

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The circumference is 2 pi times the radius which is equal to 2 pi

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and in the previous video, we figured out the radius was 6 m

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So it's 2 pi times 6 m which is equal to 12 pi meters

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If you wanted to figure out its average speed--

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the velocity is constantly changing because the direction is changing

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but the magnitude of the velocity--

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if we wanted to figure out the average magnitude of the velocity or the average speed

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the total distance traveled is 12 pi meters

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divided by the time required to travel the 12 pi meters

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so that is 2 and 14/30 seconds

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Now let's get our calculator out to actual calculate that value

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So we're going to have the distance 12 pi m divided by

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2 + 14/30 just to get the exact value

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And then this gives us in meters per second

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15.3 m/s

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So the average speed is approximately 15.3 m/s

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which is almost twice as fast as the minimum speed we figured out

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because you want that margin of safety

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and you want to be able to have some traction with the road

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Although you don't want to go too fast, because then the G force is going to be too big

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then this--maybe we'll talk about that in the future video

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I'll just relate this into kilometers per hour. Let's figure out what that is

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I want to use the calculator here

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So that's in the meters per second

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Let's figure out how many meters per hour by multiplying it by 3600 seconds per hour

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So that's how many meters per hour, and divide it by 1000 which you can see right over there

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that is 55 km/h

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If you want to do it in miles, it's rough approximation, divide it by 1.6

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It's about 35 mph give or take or 55 km/h

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So this is approximately 55 km/h

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So the driver here luckily they did the physics ahead of time

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and he had the margin of safety

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He was well in excess of the minimum velocity just to maintain the circular motion

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So he probably has some nice traction with the track up here