harry potter and the prisoner of askaban: the knight bus by: amanda speed pd.3
TRANSCRIPT
Harry Potter and the Prisoner of Askaban: The Knight Bus
By: Amanda Speed pd.3
By: Amanda Speed
Scene Description
● Harry Potter decides to take a ride on the magical Knight Bus. This bus defies gravity many times during the scene.
– The braking force of this speed is too great
– The stopping distance of the bus going this velocity would require a much longer stopping distance
– The time is still wrong in order to stop within this distance
– The force to stop in the movie does not match up with the actual force it would take the bus to stop
– Harry should fly through the windshield after stopping that instantly
Physics Concepts
Stopping distance of bus
● Determine velocity of bus using a distance interval and the travel time of that interval
● Determine the bus' momentum with momentum formula
● Impulse momentum theorem to determine the braking force needed to stop the bus
● Braking force to stop bus in the time it stops in movie
● Find actual stopping distance for time in movie
●More Physics Concepts
Force to stop a bus going this speed
● Determine force of friction
● Determine net force (ma)
Prove windshield would break
● Impulse momentum to determine force at which Harry would be traveling
● Compare to force it takes to break a windshield
Estimations
● 1 city block~ 100,000 sq.ft.
● 1.93s to travel 1 block
● 20,360kg estimate for triple decker bus
● Average male mass: 70kg
● About 10 passengers on bus (70kg each)
● 100kg for fuel tank
● 5m estimated distance bus takes to stop
● 1.5s estimate stop time of buss in scene
● .055s estimate time face hits glass for
Calculations
Timing the bus as it travels
● 1 city block~ 100,000sq ft
● = 223.62ft
● = 74.54m
● Velocity=
● V=
● V= 38.6218
Determining the mass of the bus● 1 double decker bus~ 14,560kg +● 1000kg extra floor +● 70kg per person x 10 people +● 100kg fuel tank and fuel = 20,360kg estimate mass of triple decker
bus
Braking force of the bus in the sceneImpulse Momentum Theorem:
Stopping distance the bus needs in the scene to avoid collision with the woman● Kinematic equation:● ● ●
Time the bus should take to stop if it does only have about 5m like the scene
Time the bus would take to stop within the 5m
Determining the force needed to stop the bus in the sceneCoefficient of friction: Fnet=Fapp-Fk= µFn
• Fnet=ma (acceleration= ) Fnet=20,360() Fnet=1,572,679.696N
• Rubber on wet concrete: µs=0, µk=.5 Fk=µkFn (Fn=mg) Fk=.5(20,360×9.81) Fk=99,865.8N
• Fnet=Fapp-Fk
1,572,679.696=Fapp-99,865.8 Fapp=1,672,545.496N ~1,6722.5455kN to stop the bus
Harry would crash through the windshield during brake of the bus
Momentum: F∆t=mvf-mvi
-Convert into lbs /10 ×2.2= 10,814.104lbs
120-200N/mm2 =Force needed to break a windshield
● The braking force of this speed is too great for the bus
● The stopping distance of the bus going this velocity would require a much longer stopping distance
– ~5m in movie, but it would need 28.97m● The time is still wrong in order to stop within this distance
● Only a quarter of a second of time can pass to have a 5m stopping distance
● The force to stop in the movie does not match up with the actual force it would take the bus to stop
– ~524kN to stop in the movie, it should take ~1,000kN to stop in real life● Harry should fly through the windshield after stopping that instantly
– 49,155.0181N of force greatly exceeds the 120-200N Force needed to break a windshield
Works Cited
● "AEC Regent III RT." Wikipedia. Wikimedia Foundation, 25 Mar. 2012. Web. 04 Apr. 2012. <http://en.wikipedia.org/wiki/AEC_Regent_III_RT>
● "City Blocks Differ in Size." Click Here to Support Our Advertiser. Web. 20 Apr. 2012. <http://www.land4ever.com/block.htm>.
● "Knight Bus." Knight Bus- Hary Potter Wiki. Wikja Entertainment. Web. 4 Apr. 2012. <http://harrypotter.wikia.com/wiki/Knight_Bus>.
Works Cited
● "London Bus Museum." 1952 AEC Regent III Bus â ��RT3491 -. The London Bus Preservation Trust Ltd. Web. 04 Apr. 2012. <http://www.londonbusmuseum.com/museum-exhibits/double-deck-buses/aec-regent-iii-rt-rt-3491/>.
● Yirka, Tonya. "Tempered Glass Strength Specifications." EHow. Demand Media, 29 Nov. 2010. Web. 21 Apr. 2012. <http://www.ehow.com/list_7575774_tempered-glass-strength-specifications.html>.
Works CitedPictures:
– http://news.bbc.co.uk/cbbcnews/hi/pictures/galleries/newsid_2821000/2821417.stm
– http://www.google.com/imgres?q=the+knight+bus&um=1&hl=en&sa=N&qscrl=1&nord=1&rlz=1T4ADSA_enUS373US374&biw=1024&bih=569&tbm=isch&tbnid=BOtF3rh9PhTGXM:&imgrefurl=http://wizardinglife.com/2011/09/wizarding-methods-of-travel-evaluated/&docid=v_yLM3MO1TWT9M&imgurl=http://wizardinglife.com/wp-content/uploads/2011/09/knight-bus.jpg&w=400&h=339&ei=kwWWT_zXE4qN6QHop-DGDg&zoom=1&iact=rc&dur=171&sig=112332215653833233722&page=2&tbnh=170&tbnw=219&start=8&ndsp=13&ved=1t:429,r:2,s:8,i:110&tx=134&ty=157
– http://www.google.com/imgres?q=harry+potter+and+the+prisoner+of+azkaban&um=1&hl=en&sa=X&qscrl=1&nord=1&rlz=1T4ADSA_enUS373US374&biw=1024&bih=569&tbm=isch&tbnid=TK_tNWBTIEnggM:&imgrefurl=http://www.rottentomatoes.com/m/harry_potter_and_the_prisoner_of_azkaban/&docid=nHO-XaARcUHyfM&imgurl=http://content6.flixster.com/movie/10/93/71/10937100_det.jpg&w=180&h=266&ei=1waWT9SoCuW26QH26ryODg&zoom=1&iact=rc&dur=688&sig=112332215653833233722&page=1&tbnh=165&tbnw=112&start=0&ndsp=13&ved=1t:429,r:16,s:0,i:139&tx=88&ty=108
– http://wiki.answers.com/Q/What_is_the_weight_of_a_double_decker_bus
– http://hypertextbook.com/facts/2006/DanielTouger.shtml
– http://www.google.com/imgres?q=the+knight+bus&start=188&um=1&hl=en&biw=1249&bih=592&addh=36&tbm=isch&tbnid=Bg0buyu5CRo-FM:&imgrefurl=http://news.bbc.co.uk/cbbcnews/hi/pictures/galleries/newsid_3552000/3552585.stm&docid=h3sAspC-ViRAUM&imgurl=http://news.bbc.co.uk/media/images/39963000/jpg/_39963687_harryonknightbus2.jpg&w=350&h=250&ei=ar2gT4fBAaT50gGB642yCQ&zoom=1&iact=rc&dur=292&sig=107901962098801536091&page=8&tbnh=141&tbnw=201&ndsp=26&ved=1t:429,r:6,s:188,i:18&tx=147&ty=52
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• http://www.google.com/imgres?q=the+knight+bus&start=123&um=1&hl=en&safe=active&sa=N&tbm=isch&tbnid=GLig9Xc8lzlZSM:&imgrefurl=http://wizardinglife.com/2011/01/loved-ones-say-goodbye-to-beloved-knight-bus-driver/&docid=skhwNqaYBwJi5M&imgurl=http://wizardinglife.com/wp-content/uploads/2011/01/jimmy_gardner_news_jpg_display.jpg&w=300&h=217&ei=UauWT9faCOXh0QHZvIHTDg&zoom=1&biw=1280&bih=599&iact=rc&dur=344&sig=108550289589178820660&page=6&tbnh=126&tbnw=173&ndsp=26&ved=1t:429,r:4,s:123,i:66&tx=90&ty=101
• http://www.google.com/imgres?q=harry+potter+and+the+prisoner+of+azkaban&um=1&hl=en&sa=N&biw=1249&bih=592&tbm=isch&tbnid=h4D7ENHgA4-v_M:&imgrefurl=http://www.fanpop.com/spots/harry-potter/images/5026234/title/harry-potter-prisoner-azkaban&docid=1VxBRpr2wB3P8M&imgurl=http://images2.fanpop.com/images/photos/5000000/Harry-Potter-and-the-Prisoner-of-Azkaban-harry-potter-5026234-720-480.jpg&w=720&h=480&ei=4rqgT77EEsaPgwf7g72mCQ&zoom=1&iact=hc&vpx=280&vpy=282&dur=642&hovh=183&hovw=275&tx=180&ty=140&sig=107901962098801536091&page=3&tbnh=124&tbnw=165&start=54&ndsp=26&ved=1t:429,r:14,s:54,i:288
• http://www.google.com/imgres?q=the+knight+bus&um=1&hl=en&biw=1249&bih=592&tbm=isch&tbnid=LWLXySw5O6_sPM:&imgrefurl=http://www.hp-lexicon.org/wizworld/knight_bus.html&docid=Cv_EwDrkftqLAM&imgurl=http://www.hp-lexicon.org/images/chapters/pa/c03--the-knight-bus.jpg&w=350&h=334&ei=jbygT8XqNcbg0QH__vGcCQ&zoom=1&iact=rc&dur=103&sig=107901962098801536091&page=1&tbnh=109&tbnw=114&start=0&ndsp=24&ved=1t:429,r:0,s:0,i:81&tx=61&ty=67
• http://www.google.com/imgres?q=the+knight+bus&um=1&hl=en&biw=1249&bih=592&tbm=isch&tbnid=pIUVUzUoFFuRpM:&imgrefurl=http://www.david-edward-byrd.com/warners7-3.html&docid=RIAblzz4qEXKqM&imgurl=http://www.david-edward-byrd.com/gallery/warners7-3-lrg.jpg&w=300&h=392&ei=jbygT8XqNcbg0QH__vGcCQ&zoom=1&iact=rc&dur=217&sig=107901962098801536091&page=2&tbnh=138&tbnw=113&start=24&ndsp=28&ved=1t:429,r:1,s:24,i:141&tx=77&ty=117
• http://www.google.com/imgres?q=wet+road&um=1&hl=en&biw=1249&bih=592&tbm=isch&tbnid=JvqOtqYsTtpBuM:&imgrefurl=http://www.wunderground.com/wximage/viewsingleimage.html%3Fmode%3Dsingleimage%26handle%3Dgemini%26number%3D1227&docid=zl3gLEiMFwJw_M&imgurl=http://icons-ak.wunderground.com/data/wximagenew/g/gemini/1227.jpg&w=640&h=421&ei=i76gT5qlKeT40gH7vp2LCQ&zoom=1&iact=hc&vpx=94&vpy=177&dur=122&hovh=182&hovw=277&tx=160&ty=111&sig=107901962098801536091&page=1&tbnh=112&tbnw=149&start=0&ndsp=21&ved=1t:429,r:0,s:0,i:120
• http://www.google.com/imgres?q=shattered+glass&um=1&hl=en&biw=1249&bih=592&tbm=isch&tbnid=V7FPEdym0sYXwM:&imgrefurl=http://newmichael.com/shattered-glass&docid=FfjZHDoREwHk9M&imgurl=http://newmichael.com/wp-content/uploads/2012/02/Shattered-Glass2.jpg&w=400&h=300&ei=-cOgT-nlIpK-gAemwuC7CQ&zoom=1&iact=hc&vpx=358&vpy=173&dur=1121&hovh=194&hovw=259&tx=152&ty=128&sig=107901962098801536091&page=1&tbnh=114&tbnw=152&start=0&ndsp=23&ved=1t:429,r:2,s:0,i:137
• http://www.google.com/imgres?q=woman+in+front+of+bus&um=1&hl=en&biw=1249&bih=592&tbm=isch&tbnid=Hc7bYlCtuLYvtM:&imgrefurl=http://newsfeed.time.com/2011/10/21/a-new-york-city-bus-gives-women-the-back-seat/&docid=uGoBMatDfIhvkM&imgurl=http://timenewsfeed.files.wordpress.com/2011/10/new_york_bus.jpg%253Fw%253D455%2526h%253D376%2526crop%253D1&w=455&h=376&ei=F8WgT9pmj7vQAa7m5akJ&zoom=1&iact=rc&dur=1&sig=107901962098801536091&page=1&tbnh=122&tbnw=148&start=0&ndsp=21&ved=1t:429,r:14,s:0,i:97&tx=100&ty=41