HELLO. school has started up again. so that means my questions begin to appear again. please help me!!!!! thanks!!
Hot air balloons are based on a very basic scientific principle: warmer air rises in cooler air. Why do you think hot air rises in cooler air?
What is the difference between pressure and weight?
2007-01-03 15:48:04 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Hot air rises in cooler air because it is less dense. Just as things less dense than water float on water, so too does the less dense hot air float on more dense cool air.
The difference between pressure and weight is that pressure is essentially gravity free and is caused by energetic molecules crashing into each other. Weight is dependant on mass and the gravitational field that that mass is in, it is largely independant of the amount of energy that the mass contains. A hot and a cold penny will weigh essentially the same.
2007-01-03 15:52:53 · answer #1 · answered by xaviar_onasis 5 · 0⤊ 0⤋
Hot air rises because it is less dense. Gases expand when heated. Second question: weight is pressure times the area over which it is applied, although this is usually stated in the entirely equivalent form of pressure equals weight divided by the area over which it is applied.
2007-01-03 23:52:27 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Hot air is less dense than cold air so it floats, just as oil or ivory soap float on water.
Pressure is normally thought of as pounds or some other unit of force per unit area, pounds per square foot. Weight is the force applied from gravity by an object with mass so it is pounds.
2007-01-03 23:55:17 · answer #3 · answered by Mike1942f 7 · 0⤊ 0⤋