Work and power when lifting weights

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SUMMARY

The discussion focuses on the mechanics of lifting weights, specifically comparing the energy used when lifting one end of a log versus lifting the entire log. It establishes that lifting one end utilizes a second-order lever system, which requires less energy due to the mechanical advantage gained from the fulcrum position. In contrast, lifting the log from the center employs a third-order lever system, resulting in greater energy expenditure. The mechanical energy remains constant in both scenarios, but the method of lifting significantly impacts the effort required.

PREREQUISITES
  • Understanding of lever systems, specifically first, second, and third-order levers.
  • Basic principles of mechanical energy and work.
  • Knowledge of center of mass and its significance in physics.
  • Familiarity with gravitational forces and their effects on lifting objects.
NEXT STEPS
  • Research the principles of levers and their mechanical advantages.
  • Study the concept of center of mass in various objects.
  • Learn about the relationship between work, energy, and power in physics.
  • Explore practical applications of lever systems in engineering and biomechanics.
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This discussion is beneficial for physics students, fitness enthusiasts, and anyone interested in understanding the mechanics of lifting and the principles of energy efficiency in physical activities.

physicscholar
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something i can't grasp is
why is it that when you lift one end of a log and the center of mass is raised a certain height you are using less energy than lifting the whole log with the center of mass raised to the same height
does it have to do with the amount of mass you're raising?
 
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Are you talking about the mechanical energy done on the log or the chemical energy used by your muscles? The mechanical energy is equal in the two cases.

I'm also unsure of how this relates to the title of the thread - you didn't ask anything about power.
 
Hi
if i understand properly your question...i think you must understand the gravity and balancing methods..
For e.g.,
case 1. When you lift from one end->it means a 2nd order lever (load is the log or somewhere in log, fulcrum (fixed) at the other end and)..
case 2. When you lift by holding the log somewhere (not from end!)->it means a 3rd order lever (load is the log or somewhere in log, fulcrum (fixed) where you hold the log..
Obviously it will easier in 1.
Hope this helps.
 

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