# Harry Potter and the Prisoner of Askaban: The Knight Bus By: Amanda Speed pd.3.

## Presentation on theme: "Harry Potter and the Prisoner of Askaban: The Knight Bus By: Amanda Speed pd.3."— Presentation transcript:

Harry Potter and the Prisoner of Askaban: The Knight Bus By: Amanda Speed pd.3

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

The Scene The Knight Bus

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

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 scene Impulse Momentum Theorem:

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. "City Blocks Differ in Size." Click Here to Support Our Advertiser. Web. 20 Apr. 2012.. "Knight Bus." Knight Bus- Hary Potter Wiki. Wikja Entertainment. Web. 4 Apr. 2012..

Works Cited "London Bus Museum." 1952 AEC Regent III Bus â RT3491 -. The London Bus Preservation Trust Ltd. Web. 04 Apr. 2012.. Yirka, Tonya. "Tempered Glass Strength Specifications." EHow. Demand Media, 29 Nov. 2010. Web. 21 Apr. 2012..