Final answer:
This response details how to calculate the power a trainee supplies during a pull-up by using the mass, acceleration due to gravity, estimated distance, and time to raise the body above the bar.
Step-by-step explanation:
The student is asking about how long to rest after attempting a one-repetition maximum (1 RM) lift before trying the next trial. This is related to exercise and training practices in the context of physical education, which can be associated with health or athletics. However, the reference information provided pertains to a physics problem about calculating power during a pull-up exercise done by an army trainee. To calculate the power supplied by the trainee's muscles during the pull-up, you use the formula:
Power = Work / Time
To find the work done, you would use the formula:
Work = Force × Distance
The force is equal to the trainee's weight (due to gravity), which can be calculated by multiplying the mass (80 kg) by the acceleration due to gravity (approximately 9.8 m/s^2). The calculation is as follows:
Force = 80 kg × 9.8 m/s^2 = 784 N
Next, we need to estimate the distance the trainee's body travels during one pull-up. If you estimate this distance to be around 0.7 meters (a reasonable estimate for a full pull-up motion), then the work can be calculated like this:
Work = 784 N × 0.7 m = 548.8 J
Finally, with the given time of 0.8 seconds, the power supplied is:
Power = 548.8 J / 0.8 s = 686 W (watts)
Thus, the muscles supply a power of approximately 686 watts during the pull-up. Keep in mind that this calculation involves some reasonable assumptions and simplifications for the sake of the exercise.