Should you explain in classical mechanics a moving body with constant speed has no force?

Should you explain in classical mechanics a moving body with constant speed has no force?

From classical mechanics, we know that the force is the rate of change of momentum, one of it’s simplest forms is F=ma, so if a body moves with constant velocity, then its acceleration is zero, and by the previous definition has no force, although for example if a car of constant speed strikes some person, he may be …

How is PMV calculated?

PMV is calculated on the basis of 4 measurable quantities (air velocity, air temperature, mean radiant temperature and relative humidity) and 2 expected parameters (clothing and metabolism rate), Vote generated from PMV is also considered as index value to determine the thermal sensation of the subject as shown in fig.

What is PMV thermal comfort?

The predicted mean vote (PMV) was developed by Povl Ole Fanger at Kansas State University and the Technical University of Denmark as an empirical fit to the human sensation of thermal comfort. It predicts the average vote of a large group of people on the a seven-point thermal sensation scale where: +3 = hot. +2 = warm.

How do you maintain thermal comfort?

4 ways thermal comfort can be achieved through good design, construction, and maintenance

1. Use a HVAC system that regulates MRT.
2. Minimise leakage.
3. Design and build for some occupant control.
4. Maintain the thermal environment, and make changes as necessary.

How does temperature affect human comfort?

Air velocity is an important factor in thermal comfort for example: still or stagnant air in indoor environments that are artificially heated may cause people to feel stuffy. moving air in warm or humid conditions can increase heat loss through convection without any change in air temperature.

Why thermal comfort is important?

Thermal Comfort improve Quality of Life and Health Room with good thermal comfort can improve the quality-related activities such as physical exercise. Besides the room temperature heat can cause the body tired and dehydrated. In extreme conditions and if the conditions are unfavorable body it can cause death.

How does age affect thermal comfort?

There is a lack of studies that describe the effect of aging on thermal comfort and productivity during a moderate temperature drift. The results indicate that thermal sensation of the elderly was, in general, 0.5 scale units lower in comparison with their younger counterparts.

What is thermal discomfort in buildings?

Thermal discomfort is not just a lack of satisfaction with the ambient temperature but. reflects a situation where there is a potential threat to health – that is when the. temperature falls below 18. o. C or rises above 24.

What are the four comfort factors?

Let’s look at all four factors of comfort now:

• Temperature. How hot or cold is it? Humans like to be in the range of 70 to 80 degrees, more or less.
• Humidity. How much moisture is in the air? Forty to sixty percent relative humidity is the ideal range.

What are the five factors that affect HVAC comfort?

Proper temperature and airflow are necessary to properly heat and cool a room….DUCT TEMPERATURE LOSS

• No insulation;
• Poor duct location, like a 140° attic;
• Inflated R-value ratings of the insulation type you use;
• Improper installation of duct insulation; and.
• Return duct leakage pulling in unconditioned air.

What are the important factors that affect human comfort?

Factors Affecting Human Comfort Include: Air temperature is the most significant ambient factor which affects our internal temperature and our level of comfort. But, it is not the only factor involved; air speed, humidity and mean radiant temperature must also be considered.