Three part weightlifter question

  • Thread starter physicsgurl12
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In summary, a weightlifter performs a daily workout routine that includes lifting a 40kg barbell at a distance of .50m. Using the work energy theorem and the acceleration of gravity, the weightlifter expends a certain amount of work, which can be calculated using the given information. Assuming a 25% efficiency, the weightlifter would expend a certain amount of total energy for 20 reps a day. Based on this energy expenditure, it can be calculated that the weightlifter could consume a certain number of 400 calorie donuts per day to supply that energy.
  • #1
physicsgurl12
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Homework Statement



A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 40kg barbell straight up at a distance of .50m.
a. how much work does the weightlifter do to lift the barbell one time?
b. if the weightlifter does 20 reps a day what total energy does she expend on lifting? assume 25% efficency.
c. How many 400 calorie donuts can she eat a day to supply that energy.

Homework Equations



w=fd f=ma


The Attempt at a Solution


w=fd w=f*.50m
f=40kg*a ?/
 
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  • #2
Use the work energy theorem, the barbell has zero velocity at both the top and bottom of the rep.
 
  • #3
Your acceleration "a" is the acceleration of gravity: g=9.8 m/s2.
With what you already have you should be able to find the work w...
 

1. What is the three part weightlifter question?

The three part weightlifter question is a hypothetical scenario used in physics and biomechanics to study the forces and mechanics involved in weightlifting. It consists of three parts: the initial lift, the pause, and the final lift.

2. How does the three part weightlifter question relate to real-life weightlifting?

The three part weightlifter question is a simplified version of a real-life weightlifting motion, where the initial lift represents the weightlifter picking up the weight, the pause represents the weightlifter holding the weight in a stationary position, and the final lift represents the weightlifter completing the lift and placing the weight back down. It allows scientists to study the mechanics of weightlifting without the complexity of real-life variables.

3. What types of forces are involved in the three part weightlifter question?

There are three types of forces involved in the three part weightlifter question: the weight of the barbell, the force exerted by the weightlifter's muscles, and the force of gravity. These forces act in different directions and magnitudes throughout the three parts of the motion.

4. What can the three part weightlifter question tell us about weightlifting?

The three part weightlifter question can provide insights into the biomechanics of weightlifting, such as the forces and angles involved in different parts of the motion. It can also help identify areas for improvement in a weightlifter's technique, as well as inform the design of weightlifting equipment.

5. How is the three part weightlifter question used in research?

The three part weightlifter question is used in research to study the mechanics and forces involved in weightlifting. Scientists can manipulate various factors, such as the weight of the barbell or the angle of the lift, to see how they affect the overall motion and the forces involved. This information can be used to improve training techniques and prevent injuries in weightlifting.

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