Hooliganism of the Day: Fifth Gear Guys Attempt Loop the Loop
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Hooliganism of the Day: Fifth Gear Guys Attempt Loop the Loop
Replicating the clasic Hot Wheels set, Fifth Gear TV attempts to perform a full 360 degree loop in a full size car.
http://www.youtube.com/watch?v=wiZoV...layer_embedded
http://www.youtube.com/watch?v=wiZoV...layer_embedded
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looks like fun
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Your Friendly Canadian
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From: Toronto, Ontario
Maybe it's just me, but it definetely looks like he was on the verge of falling off at the top of the loop there. 36 mph seemed a bit too slow for me, but I guess it worked. I think I'd go about 40 though, just to be on the safe side. I don't know how he remembered to steer though. I wouldn't.
Someday, an RS6 Avant+
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No physicist, but a simple accelerometer would bear out what this was all about (I do a little bit of rocket science, if that counts).
If you watched the ending, the professor said that if he went 1mph faster, because of the rear overhang, the scrapping would have caused the car to fall. So he really needed to be in the 36-38 MPH range.
If you watched the ending, the professor said that if he went 1mph faster, because of the rear overhang, the scrapping would have caused the car to fall. So he really needed to be in the 36-38 MPH range.
E92
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From: socal
In equation terms, the force F is described by the equation F = mv^2/r where m is the mass of the object, v is it's speed, and r is the radius of the loop. For the car to stay on the loop, this force must be greater than the force of gravity pulling the car down. For this situation, the equation would be mg=mv^2/r, and the mass of the car would cancel out of the equation making it g=v^2/r, meaning that theoretically he could have done the same loop in a semi truck at 36 mph and still have completed it. It gets more complicated though when you consider how the car will slow down as it goes up the ramp, but you can factor that in by using conservation of energy to find the new velocity at the top of the loop. This is dependent on initial velocity and the height of the loop.
When you factor in the loss of speed at the top, you get the equation 2v^2/h = 5g, where h is the height of the loop, v is the initial velocity, and g is the gravitational acceleration. Using 40 feet for the approximate height of the loop gives an initial velocity of 38 mph, close to what they did in the video.
Notice how the force exerted on the person goes like the square of the velocity, so if he went twice as fast at 70 mph, he would have felt 24 g's
Last edited by TommySalami; Dec 5, 2009 at 10:52 PM.
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What's keeping the car planted against the loop as he's at the top is a centripetal force, from the motion of him rotating about the inside of the loop. It's the same reason why, when you take a hard left turn, your body gets pushed to the right. The faster he goes, the more force it exerts because it's a quicker rotation. The harder the turn, the more you get thrown around inside your car, which is why if he went too fast, the G's would make him black out.
In equation terms, the force F is described by the equation F = mv^2/r where m is the mass of the object, v is it's speed, and r is the radius of the loop. For the car to stay on the loop, this force must be greater than the force of gravity pulling the car down. For this situation, the equation would be mg=mv^2/r, and the mass of the car would cancel out of the equation making it g=v^2/r, meaning that theoretically he could have done the same loop in a semi truck at 36 mph and still have completed it. It gets more complicated though when you consider how the car will slow down as it goes up the ramp, but you can factor that in by using conservation of energy to find the new velocity at the top of the loop. This is dependent on initial velocity and the height of the loop.
When you factor in the loss of speed at the top, you get the equation 2v^2/h = 5g, where h is the height of the loop, v is the initial velocity, and g is the gravitational acceleration. Using 40 feet for the approximate height of the loop gives an initial velocity of 38 mph, close to what they did in the video.
Notice how the force exerted on the person goes like the square of the velocity, so if he went twice as fast at 70 mph, he would have felt 24 g's
In equation terms, the force F is described by the equation F = mv^2/r where m is the mass of the object, v is it's speed, and r is the radius of the loop. For the car to stay on the loop, this force must be greater than the force of gravity pulling the car down. For this situation, the equation would be mg=mv^2/r, and the mass of the car would cancel out of the equation making it g=v^2/r, meaning that theoretically he could have done the same loop in a semi truck at 36 mph and still have completed it. It gets more complicated though when you consider how the car will slow down as it goes up the ramp, but you can factor that in by using conservation of energy to find the new velocity at the top of the loop. This is dependent on initial velocity and the height of the loop.
When you factor in the loss of speed at the top, you get the equation 2v^2/h = 5g, where h is the height of the loop, v is the initial velocity, and g is the gravitational acceleration. Using 40 feet for the approximate height of the loop gives an initial velocity of 38 mph, close to what they did in the video.
Notice how the force exerted on the person goes like the square of the velocity, so if he went twice as fast at 70 mph, he would have felt 24 g's
Dayum, TS...you an engineer?
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Coolest. Stunt. Ever.
That's one of those things you fantasize about as a 6 year old (before the knowledge of girls permanently clouds all rational thought) playing with those hotwheels tracks.
The old engineering geek in me is amazed that they were able to get "real life" to match up to the "ideal" equations. I'm glad they did their math and it worked, otherwise it could have been a disaster. That driver had to have great trust - my instinct would have been to floor it and pray!
That's one of those things you fantasize about as a 6 year old (before the knowledge of girls permanently clouds all rational thought) playing with those hotwheels tracks.
The old engineering geek in me is amazed that they were able to get "real life" to match up to the "ideal" equations. I'm glad they did their math and it worked, otherwise it could have been a disaster. That driver had to have great trust - my instinct would have been to floor it and pray!
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