Calculating Human Power in Weightlifting: A Detailed Analysis
When considering the efficiency and physical prowess of a weightlifter, one interesting exercise is to determine the wattage of a weightlifter during the execution of a particular movement. In this article, we will walk through the process of calculating the human power in watts required to lift a 200kg weight over head from the floor level to a height of 205cm in 10 seconds.
Understanding the Physics
Power is defined as the rate at which work is done. The formula for power is given by:
Power (W) Work (J) / Time (s)
Where work (J) is calculated as:
Work (J) Force (N) times; Distance (m)
The Given Problem
The problem at hand is as follows:
A weightlifter weighs 100kg and has a height of 175cm. Calculate the human power in watts needed to lift a 200kg weight over his head 205cm high within 10 seconds from the floor level.
Calculating the Work Done
To solve this problem, we need to first determine the force required to lift the 200kg weight and then calculate the distance the weight is moved. The force can be calculated using the formula:
Force (N) Mass (kg) times; Gravity (m/s2)
Given the mass is 200kg and the acceleration due to gravity (g) is approximately 9.81 m/s2, the force is:
Force 200 times; 9.81 19620N
The Distance Mismatch
However, calculating the distance is more complex. The problem states that the weight is lifted to a height of 205cm, but the initial position is the floor level. In practice, a weightlifter does not lift the weight from the floor but from a position a few inches above the ground. Observing a weightlifting video, we see the bar starts about 23cm above the ground. Therefore, the actual distance the weight is moved is:
Distance 205 - 23 182cm 1.82m
The Work Done
The work done in lifting the weight is given by:
Work Force times; Distance 19620 times; 1.82 3569.748 J (or Nm)
The Power Requirement
Given the time taken to lift the weight is 10 seconds, the power required can be calculated as:
Power Work / Time 3569.748 / 10 356.9748 W
Understanding the Complexity
However, this calculation does not account for several factors:
The weightlifter could not lift the weight in 10 seconds. The actual path may not be a straight lift. The body movement of the weightlifter, including the use of legs and core muscles which are not fully accounted for.Considering a more realistic scenario where the weightlift takes approximately 4 seconds to lift the weight according to a world record holder, the power required would be:
Power Work / Time 3569.748 / 4 892.437 W
Conclusion
In conclusion, while the initial calculations suggest a lower wattage requirement, a more realistic and detailed analysis shows a significantly higher power output. This highlights the importance of understanding the real-world factors affecting performance in weightlifting.