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Athlete or Machine? Presented by Dominic Nolan. The Royal Academy of Engineering

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Investigate the big question: athlete or machine? Practical activities and testing Mathematics activities Science activities Engineer/athlete video Student led Independent investigation Higher level thinking Scheme of work for STEM day or STEM club

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Make a 1:5 bob skeleton sled 90 minute make Cheap materials Basic tools and equipment

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Make a launcher

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Make some timing gates (if you have the time) Achieving launch pressure consistency

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Bob Skeleton 1500m track 150 m vertical drop 143 km/h (40 m/s, 89 mph) Athletes times differ by tenths of seconds Rules for sleds dimensions, mass and materials 33 – 43 kg sled Amy Williams - Olympic gold 2010

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CHALLENGE Make a model of a bob skeleton sled See how far you can launch a Barbie! Present an answer to the question: Athlete or Machine? Which is more important in the sport of bob skeleton?

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Make a 1:5 bob skeleton sled Make the runners by bending the metal rod Attach runners to pod with cable ties Make sleds launch tube using acetate sheet, tape and a plastic nose cone (check that it fits onto the pumps launch tube) Fix the launch tube to the pod with double-sided sticky pads

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Launch the model bob skeleton sled. Launch Barbie!

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Factors Weight The athletes shape The athletes position Aerodynamic lift Steering Clothing and equipment Starting Corners Ergonomics (how the body fits a product) Track incline (the slope down the length of the track) Friction on the ice Aerodynamic drag (air resistance) Tuning the characteristics of the skeleton Material choice Sled runners

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Potential Energy (PE) = m x g x h Change in PE for our athlete and sled = Joules (J) Kinetic Energy (KE) = ½ x m x v x 97 kg x (40.23 x 40.23) = J Amy Williams max speed Max speed if all PE transferred into KE Mass (m) of athlete and sled = 97kg Vertical drop of track (h) = 152m 1450m (diagram not to scale) Gravity (g) = 9.81 m/s 2 Energy transfer Why isnt the all of the athletes and sleds potential energy transferred into kinetic energy?

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Calculating friction force F f = x m x g F f = ………………………… =Mu, the coefficient of friction (steel on ice = 0.03). m =Mass (kg). g =The acceleration due to the gravity, which is 9.81 m/s 2. What is the friction force acting on the runners of a bob skeleton sled and athlete with the combined mass of 97 kg (athlete = 68 kg, sled = 29 kg)?

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Calculating drag force F DRAG = ½ x x C D x A f x V 2 F DRAG = …………………………. =1.2 kg/m 3 (density of air) C D =0.45(drag coefficient of athlete and sled) A f =0.139 m 2 (frontal area of athlete and sled) V =40 m/s(velocity) Calculate the drag force acting on the athlete and sled as they travel down the track at 40 m/s?

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What is the total force resisting the forward movement of the athlete and her sled down the track? F TOTAL = …………………………………… Between which velocities is friction force dominant? ……………………………………………….. Between which velocities is drag force dominant? ……………………………………………….. You can compare the two forces on the graph here Speed in metres/second (m/s) Force in Newtons (N)

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Prove that it is better to be heavy and narrow when competing in The sport of bob skeleton. ATHLETE 1 Total mass: 97 kg A f : m 2 ATHLETE 2 Total mass: 100 kg A f : m 2

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Athlete or Machine? Which is more important in the sport of bob skeleton? Discuss this question with your partner/team Present your answer to the rest of the group

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