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# At the fairground

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### At the fairground

1. 1. At the Fairground http://www.youtube.com/watch?v=8XQzQYFYfy8
2. 2. What we are covering today • When is the contact force on a passenger greatest on a rollercoaster • How do you keep a passenger in their seats while giving a white knuckle ride
3. 3. The First Drop Weight W Support force S Centre of curvature What is the support force you will feel at the bottom of the slope? Force up = S (reaction force) Force down = mg (weight) + mv2 /r If everyone stays in their seat the forces must balance S = mg + mv2 /r This is the extra force you feel! http://www.nolimitscoaster.com/index.html
4. 4. http://www.youtube.com/watch?v=h1VBSd_8Yys&feature=related The Big Rush Cable length (L) Velocity (v) Weight (mg) Support force (s) Start position All the potential energy at the top of the swing is converted into kinetic energy at the bottom. Pe = Ke mgh = ½ mv2 V2 = 2gh The support force S = mg + mv2 /L S = mg + 2mgh/L The extra support force at the bottom of the swinghttp://phet.colorado.edu/sims/pendulum- lab/pendulum-lab_en.html
5. 5. BIG WHEELSKeep on turnin’ The ride I used to be too scared to go on A big wheel takes passengers on the inside circumference, the wheel must turn fast enough to stick the passengers to the walls so they do not fall out. A big wheel takes passengers on the inside circumference, the wheel must turn fast enough to stick the passengers to the walls so they do not fall out. At the maximum height the reaction force (R) and the weight (mg) acts downwards. Reaction force (R) The centrifugal force up must be greater than the downwards force mg + R = mv2 /rmg + R = mv2 /r r At the point the weight and centrifugal are equal there will be no reaction force At the point the weight and centrifugal are equal there will be no reaction force mg = mv2 /r v2 = grv2 = grThe wheel has to go faster thanThe wheel has to go faster than
6. 6. G - Force • After around 4g passengers start blacking out! • Rollercoaster designers have to make sure that there is never an acceleration greater than (3g) 30 m/s2 http://puzzling.caret.cam.ac.uk/game.php?game=roller http://www.youtube.com/watch?v=EXQKl-28zn0
7. 7. G - Force • After around 4g passengers start blacking out! • Rollercoaster designers have to make sure that there is never an acceleration greater than (3g) 30 m/s2 http://puzzling.caret.cam.ac.uk/game.php?game=roller http://www.youtube.com/watch?v=EXQKl-28zn0