Recent content by John Constantine

  1. J

    B Cooling effect of evaporation occurs even if the surroundings are colder?

    If a sealed space is in thermal equilibrium, how can evaporation occur? Since the process of evaporation would require the absorption of heat energy from a heat source with a relatively higher temperature than the substance attempting to evaporate, wouldn't it be impossible for evaporation to...
  2. J

    B Cooling effect of evaporation occurs even if the surroundings are colder?

    How is it possible for heat to move from a cold place to a hot place? Is this possible during a phase change? Isn't it necessary to obtain heat from a heat source that is always higher than the object undergoing the phase change?
  3. J

    B Cooling effect of evaporation occurs even if the surroundings are colder?

    Thank you for your response. While I am not an expert in the process of air conditioning cooling a room, I have a basic understanding of it. What I am curious about is whether the temperature of the refrigerant evaporating indoors must necessarily be lower than the indoor air temperature, or...
  4. J

    B Cooling effect of evaporation occurs even if the surroundings are colder?

    Even if the temperature at which the refrigerant evaporates is higher than the temperature of the room, does the refrigerant still absorb heat from the relatively cooler room?
  5. J

    B Cooling effect of evaporation occurs even if the surroundings are colder?

    I was studying the principles of air conditioning and came across some questions. In an air conditioner, the refrigerant absorbs heat while evaporating indoors, thereby lowering the temperature, and releases heat while condensing outdoors, thereby raising the temperature. According to the second...
  6. J

    I Why does the main muscle use the most energy in body movements?

    I apologize for causing confusion. I am not a physics major, just an ordinary person with a keen interest in physical phenomena, so I often use vague expressions unintentionally. I will try to clarify the problem more specifically.
  7. J

    I Why does the main muscle use the most energy in body movements?

    Yes, according to the law of conservation of energy, the total energy is not consumed but merely transformed into different forms. For example, in the case of a robotic arm, the electrical energy from the motor is converted into mechanical energy. It is not the energy that the robotic arm...
  8. J

    I Why does the main muscle use the most energy in body movements?

    The definition of energy is the ability to do work. To do work, force must be generated. Motors generate force. Robotic arms do not generate force; they merely transmit force. (Is it correct to say they "serve as conduits for transmitting energy"? This is still uncertain.) If we assume the...
  9. J

    I Why does the main muscle use the most energy in body movements?

    When considering a robotic arm lifting an object, the arm itself merely transmits force, so the actual work is done by the motors attached to the arm. The electrical energy is converted into the mechanical energy of the object. Nonetheless, by the definition of work, the arm does perform work on...
  10. J

    I Why does the main muscle use the most energy in body movements?

    This seems intuitively very correct. In interactions between objects or within organisms, if the movement is minimal or fixed, why is the energy lost also minimal? For instance, when we do rowing exercises for our back, the arms move much more than the back. Similarly, during push exercises, the...
  11. J

    I Why does the main muscle use the most energy in body movements?

    Energy is invisible and does not have a specific location but truly exist! ; it cannot be seen transferring from one place to another. Is there even a way to know how much energy each part uses or receives in such complex movements?
  12. J

    I Why does the main muscle use the most energy in body movements?

    This may seem like an obvious and foolish question intuitively, but I am curious about something. Let's assume we are performing a biceps curl exercise. To properly analyze human movement, a much more complex process is needed, but I will simplify it as much as possible. As the name of the...
  13. J

    B The work done by two objects on each other

    The work done by A on B as Wab, and the work done by B on A as Wba. I have always thought that Wab = -Wba generally always holds true. Looking at it from the perspective of energy transfer: "A do 10J of work on B." "A transfer 10J of energy to B." "B received 10J of energy from A." "B do...
  14. J

    B Curious about Work and Energy Consumption

    I understand now that only the force directly applied to the system can do work on the system. When I pull the system consisting of the string and the object through the string, strictly speaking, I am only doing work on the string and the object as a whole, not directly on the object. I am...
  15. J

    B Curious about Work and Energy Consumption

    If the force I applied to the object through the string made the object move, then considering the string and the object as one system, it means I did work on the object. In contrast, is it that the reaction force of "the force the spring applied to me," which is "the force I applied to the...
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