tag:blogger.com,1999:blog-870243446287137853.post1345336987972248069..comments2013-04-28T23:28:08.326+08:00Comments on Open Source Physics @ Singapore: What evidence(s) are there of the speed of the Ferrari was traveling at140± 30 km/hr?lookang lawrence weehttps://plus.google.com/108897123136348550823noreply@blogger.comBlogger15125tag:blogger.com,1999:blog-870243446287137853.post-82620433845729494882012-05-21T10:56:27.328+08:002012-05-21T10:56:27.328+08:00thanks Tim! updated as pointed out :)thanks Tim! updated as pointed out :)lookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-10876236388497222602012-05-21T10:26:52.601+08:002012-05-21T10:26:52.601+08:00Hi, it's "moral lesson", not "m...Hi, it's "moral lesson", not "morale lessons". An interesting effort to look at the accident. - TimAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-54025333562186876932012-05-21T09:03:44.098+08:002012-05-21T09:03:44.098+08:00agreed. got the LaTex from Wikipedia.
http://en.wi...agreed. got the LaTex from Wikipedia.<br />http://en.wikipedia.org/wiki/Velocity<br />thanks!lookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-78681616970669676382012-05-20T22:38:02.960+08:002012-05-20T22:38:02.960+08:00Appreciate the analysis man...but it ca be better ...Appreciate the analysis man...but it ca be better presented using LaTeX to keep the numerous calculations tidy..=)Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-3672408667922296782012-05-19T22:31:06.742+08:002012-05-19T22:31:06.742+08:00Taking your estimates of 140kph, that translates t...Taking your estimates of 140kph, that translates to about 40m/s. 5 seconds means 200meters up the road, presuming constant speed (an assumption which probably will hold for the short duration here). That places the Ferrrai halfway up the road to the next junction at Victoria/ Middle Road. Did he see the wrong traffic light signal?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-7060117082757347182012-05-17T23:26:56.860+08:002012-05-17T23:26:56.860+08:00Well, since you have the views for your work, I...Well, since you have the views for your work, I'll like to extend your educational aspect into logical thinking and some science trivial. <br /><br />There is roughly a 5 second difference between the light change to green in favour of the taxis, to the impact. Logical Question #1: Where is the Ferrari at the point of light change? (Obvious answer: Not at stop line of Victoria/ Rocher). <br /><br />Taking your estimates of 140kph, that translates to about 40m/s. 5 seconds means 200meters up the road, presuming constant speed (an assumption which probably will hold for the short duration here). That places the Ferrrai halfway up the road to the next junction at Victoria/ Middle Road. <br /><br />Taking the upper and lower bounds of your estimates, the Ferrari works out to be 150m to 236m up the road. If the Ferrari is actually travelling around 250KPH -- possibility given some of the issues with the video footage -- then it's actually on the far side of the Victoria/ Middle Road junction. <br /><br />(Disclaimer: all distances measured in Google Earth. Might be off a bit.)<br /><br />Logical Qn #2: Could the Taxi Driver even see the Ferrari from his position at the Stop Line when the light turn green in his favour? Do take a look down Victoria, it's actually quite cluttered at that position<br /><br />Logical Qn #3: Could the Ferrari accelerate from standing still (or "street legal") to the impact speed in the distances involved? (Implication: May not be the only red light driven through.)<br /><br />Logical Qn #4: Are there any other cameras along the street that might have captured additional footage? (Answer: At least one visible camera at Victoria/ Bras Basah junction.)<br /><br />Science Trivia time!<br /><br />Calculate the kinetic energy of the Ferrari at the point of impact; remember to state your chosen velocity. Remember to utilize SI units. Mass of Ferrari has been stated at 1605KG... empty.<br /><br />Then taking the figure derived, further derive an example that a physics layman would be able to understand the energies and forces involved. <br /><br />For example, some random calculations I did indicate that assuming not 100% energy conversion (as neither vehicle came to complete standstill and there are deformation involved). There is still sufficient energy involved that leads me to believe I could boil a whole 5 liter kettle of water with the energy.. instanteously.Unknownhttps://www.blogger.com/profile/06539959254056150011noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-18037385843048103162012-05-17T20:35:10.666+08:002012-05-17T20:35:10.666+08:00the uncertainty in your calculation comes from the...the uncertainty in your calculation comes from the 7 frames assumption, i check my video *.flv there are 9 frames.<br />assume dt = 1/30<br />t = 9*1/30 = 0.3.<br /><br />in another video *.mp4,<br />the dt = 1/25<br />there are 8 frames<br />t = 8*1/25 = 0.32<br /><br />v = 11.5/0.3 or 11.5/0.32 = 38.3 or 35.9 m/s<br />v = 138 or 130 km/hr depends on the video was encoded in what frame-rate.<br /><br />whch is quite consistent with my analysis v =140± 30 km/hrlookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-74740283326987022422012-05-17T18:06:55.799+08:002012-05-17T18:06:55.799+08:00140± 30 km/hr is the estimate that covers your est...140± 30 km/hr is the estimate that covers your estimates too :)lookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-80917182356558445822012-05-17T17:33:48.766+08:002012-05-17T17:33:48.766+08:00Unless the distance is only 8m (3.7m per lane *2 =...Unless the distance is only 8m (3.7m per lane *2 = 7.4m.. + 50-60cm = 8m)<br />Then I'll get 110.77km/h.<br /><br />Hope someone can measure the distance by pacing from White line to start of 3rd lane.Aanoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-85963381654397495792012-05-17T17:30:23.772+08:002012-05-17T17:30:23.772+08:00Sorry i forgot the distance should be of 2 lanes a...Sorry i forgot the distance should be of 2 lanes apart (since the cab is in 3rd lane), so I concur with your distance of 10m (maybe lesser).<br /><br />But I don't understand how you get 0.3s for time? <br />Base on frame by frame analysis it should be lesser than that, and i think the Time is unit is very sensitive in the calculation.<br /><br />Therefore with 10m per 0.2333 sec, its 154.31km/h. <br /><br />Thanks.Aanoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-88410691037893595022012-05-17T17:21:49.740+08:002012-05-17T17:21:49.740+08:00Hi,
My estimation differs from you, I get around ...Hi,<br /><br />My estimation differs from you, I get around 177km/h. But with the assumption on the Distance only. Time is quite fixed, no argument on that, there is a clock on the video for reference and using simple frame by frame analysis we can tell the time.<br /><br />Speed = d/t<br /><br />Time (t):<br />The video is 30 fps, this is verified by using VLC and skipping frame by pressing E. Measure it base on the clock on bottom left. Please take note pressing Five E will result in one pause. There will be 30 frames per second.<br /><br />From the time the Ferrari appear till impact, there are 7 frames.<br /><br />Each frame = 1/30sec = 0.0333 sec<br />7 frames = 0.2333 sec<br /><br />Distance (d): <br />The Ferrari first appear at the white line at crossroad.<br />Distance between each lanes = 3.7meter<br />The Taxi is 3 lanes apart = 3.7 * 3 = 11.1m<br />Let's add some distance between the White line and the beginning of the lane, say 40cm? Let's make it 11.5m for distance. <br /><br />For better accuracy, measure the width of the lane at the area * 3, and estimate White line to start of the lane and add it in.<br /><br /><br />Speed = 11.5m * 0.2333 sec <br />= 49.29m/s <br />= 177.45km/h<br />(1m/s = 3.6km/h)<br /><br />Thanks.Aanoreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-53270241665691005852012-05-17T16:43:28.456+08:002012-05-17T16:43:28.456+08:00Step 3: use tracker http://www.cabrillo.edu/~dbrow...Step 3: use tracker http://www.cabrillo.edu/~dbrown/tracker/ to open the video filelookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-23771710606347145682012-05-17T11:46:28.542+08:002012-05-17T11:46:28.542+08:00Wow... That is really sexy science. When I first s...Wow... That is really sexy science. When I first saw the accident I thought it'd be about roughly an estimated 120km/h. Cause of the skipped frame in the camera footage. (y) what program are you using? it's really cool!ryanadninhttp://ryanadnin.wordpress.com/noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-9320150964439580562012-05-16T17:59:51.423+08:002012-05-16T17:59:51.423+08:00at 6 pm 16May 2012
more comments
J Elaine: Wow, ...at 6 pm 16May 2012<br /><br />more comments<br />J Elaine: Wow, real-life authentic and applied learning!!!! ;)<br /><br />S Wee: he is the de-facto person in moe when it comes to tech in physics education here<br /><br />Jerry J Lee: icic im usually uninterested in stuff unrelated to my field, but he was able to pique my interest, so kudos to him. =)<br /><br />more shares:<br />William SilverWater via Song Wee 嚴<br />Ivan Soh and 5 others shared a link.lookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.comtag:blogger.com,1999:blog-870243446287137853.post-25318971076938346352012-05-16T14:01:35.728+08:002012-05-16T14:01:35.728+08:00after 2 hours
comments:
Walter L: Wow, that'...after 2 hours <br /><br />comments:<br /><br />Walter L: Wow, that's an impressive bit of science Lawrence!<br /><br />Ng Y H: brilliant, but i would use the approximate sign when doing approximation to various s.f.<br /><br />Jeff T: Thanks for the analysis.. i guess the assumption of the height of the green light post to base being 2 m is quite an underestimate.. i don't recall being able to reach the green light by just raising my arm.. and that means the scale of the simulation is underestimated..<br /><br />sharing <br /><br />K L: via Loo Kang Lawrence Wee<br />Expert knowledge on the speed of the Ferrari<br /><br />T YH via Loo Kang Lawrence Wee<br />for those out there seeking scientic figures on the speed of the fellali (:lookang lawrence weehttps://www.blogger.com/profile/13329357776500010774noreply@blogger.com