A 70 kg person runs at a speed of 4.50 m/s. Assume that 100 J of...

 

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A 70 kg person runs at a speed of 4.50 m/s. Assume that 100 J of kinetic energy is lost between heel contact and mid-stance. Assume also that the change in gravitational potential energy between heel contact and mid-stance is negligible. 1. What is the runner's speed at mid-stance? Enter your answer in units of m/s. 2. Assume the Achilles tendon has absorbed 32 J and the plantar fascia in the foot has absorbed 19 J at mid-stance. If the Achilles tendon returns 92% of its energy, and the plantar fascia returns 79% of its energy, how much mechanical energy must be actively generated through muscle contractions for the person to leave the ground with the same kinetic energy as was present at foot contact. (Enter your answer in units of Joules/Step) 3. Regardless of your answer above, assume that for another runner, 58.21 J/step needs to be generated. Assume this runner maintains a cadence of 170 steps per minute and muscles are 21% efficient in converting metabolic energy into mechanical energy. Estimate how many Calories are burned by propulsive muscles when running for 1 hour? (1 Calorie is equal to 4200 J). Enter your answer in units of Calories A 70 kg person runs at a speed of 4.50 m/s. Assume that 100 J of kinetic energy is lost between heel contact and mid-stance. Assume also that the change in gravitational potential energy between heel contact and mid-stance is negligible. 1. What is the runner's speed at mid-stance? Enter your answer in units of m/s. 2. Assume the Achilles tendon has absorbed 32 J and the plantar fascia in the foot has absorbed 19 J at mid-stance. If the Achilles tendon returns 92% of its energy, and the plantar fascia returns 79% of its energy, how much mechanical energy must be actively generated through muscle contractions for the person to leave the ground with the same kinetic energy as was present at foot contact. (Enter your answer in units of Joules/Step) 3. Regardless of your answer above, assume that for another runner, 58.21 J/step needs to be generated. Assume this runner maintains a cadence of 170 steps per minute and muscles are 21% efficient in converting metabolic energy into mechanical energy. Estimate how many Calories are burned by propulsive muscles when running for 1 hour? (1 Calorie is equal to 4200 J). Enter your answer in units of Calories

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