An individual performing calf raises, rising onto the balls of their feet and then lowering their heels, is an example of what class lever? 1st class 2nd class 3rd class 2. An individual performing overhead triceps extensions with a 5kg dumbbell is an example of what class lever? 1st class 2nd class 3rd class 3. A gym-goer is holding a dumbbell statically while he snaps a quick selfie in the mirror. Here is what you know: Elbow flexion angle = 90° The torque generated at the elbow due to the force of the biceps = 78.48 Nm Moment arm of the biceps = 2 cm External resistance = 20 kg Distance from the elbow joint center to the external resistance = 40 cm Note: Not all the information provided is necessary to answer the question below. However, we will revisit the gym-goer scenario in the coming weeks as we learn more about the concepts and applications of angular kinetics. What class lever is this system? 1st class 2nd class 3rd class
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- A 1st class lever has the fulcrum between the effort and the load (e.g., a seesaw). - A 2nd class lever has the load between the fulcrum and the effort (e.g., a wheelbarrow). - A 3rd class lever has the effort between the fulcrum and the load (e.g., a fishing Show more…
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Adi S.
After watching the video on levers, use the law of levers (F x FA = R x RA) to answer the following two questions (3 points each for 6 points): If the biceps brachii (forearm flexion) muscle inserts on the radial tuberosity 3.2 cm from the elbow and the length of the forearm is 32.0 cm, how much weight can be lifted if the biceps can exert 280 lbs of force? Hint: FA = 3.2 cm and RA = 32.0 cm. Note: In scientific contexts forces are usually expressed in Newtons (N) and mass is usually expressed in kilograms (kg). Both units can be easily converted to pounds which is what we are more familiar with. In the example above (same FA and RA) if the person is holding 25 lbs at 90 degrees of elbow flexion (parallel to the ground) and the biceps is exerting 240 lbs of force, which of the following statements is true? The weight will remain stationary (F x FA = R x RA) The weight will be lifted (F x FA > R x RA) The weight will be lowered (F x FA < R x RA) The weight will be thrown directly to the head of a certain professor who makes students do math problems
Ethan D.
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