Hi,
Need some help here...
1. When the main pads of a bicycle pump with the end blocked up. When a bicycle tire is pumped up, the volume of the air trapped in the pump is reduced and its pressure is increased.
(a) Explain, in term of the motion of molecules, why the pressure increases.
(b) In practice, the temperature of the air increases as it is compressed. Explain why this is so.
2. A thin-walled plastic bottle is sealed and contains dry air at atmospheric pressure
(a) Explain how the molecules of air inside the bottle exert a pressure on the wails.
(b) Ice is placed inside the bottle, and the bottle is then sealed again. The temperature of the air inside the bottle falls and the bottle becomes partially crushed. Explain, in terms of the molecules of air inside and outside the bottle, why this happens.
read ur text, got full explaination
Originally posted by blueish:Hi,
Need some help here...
1. When the main pads of a bicycle pump with the end blocked up. When a bicycle tire is pumped up, the volume of the air trapped in the pump is reduced and its pressure is increased.
(a) Explain, in term of the motion of molecules, why the pressure increases.(b) In practice, the temperature of the air increases as it is compressed. Explain why this is so.
2. A thin-walled plastic bottle is sealed and contains dry air at atmospheric pressure
(a) Explain how the molecules of air inside the bottle exert a pressure on the wails.(b) Ice is placed inside the bottle, and the bottle is then sealed again. The temperature of the air inside the bottle falls and the bottle becomes partially crushed. Explain, in terms of the molecules of air inside and outside the bottle, why this happens.
I agree with SBS n SMRT that the answer can be found in the textbook. But I shall help you out with question 2b, which I don't recall the text including the explanation.
When ice is placed in the bottle, temperature inside the bottle drops. As a result the air molecules in the bottle lose kinetic energy, moving slower and colliding against the walls of the bottle less frequently and violently. This causes pressure to decrease. Soon after, pressure in bottle becomes so low that the atmospheric pressure (the external environment) becomes larger than that in the bottle. With a resultant pressure acting on the bottle, the bottle becomes crushed.
FYI, examples like why an egg can drop into a bottle after you heat the bottle and leave the egg on top of the opening also is due to the above phenomenon. By the way, Physics is a very systematic subject. At first it appears tougher than Chemistry but when you really really find time to do more and explore more questions, you'd realise the explanations are very alike. So, practise more!
Thanks.
ah man
i tot i the 1st to reply =(
Thanks Audi..cos i left my text@school.
Is this pure phy ?
yes....