Category : Science
Manova Aug 17, 2019 0 1011
When the pressure is normal the cooking items absorb less heat and so the cooking time is high. When the pressure is high the cooking items absorb more heat faster and so the time to cook the cooking items reduced. For instance, water boils at 100 0C at 1 atmospheric pressure for a certain period of time (boiling time). When the pressure is increased the water boils at increased temperature (more than 100 0C) and the boiling time is increased. From this we can understand that when the pressure is increased the heat to be supplied is more but the cooking time is reduced. The name of the pressure cooker itself explains that cooker cooks at some high pressure. So closing the lid of the cooker we don’t allow more steam to escape and thus the pressure of the cooker increases. The heat spreads much faster and the cooking also is done faster than normal cooking.
Why does a water bottle or 20 or 25 litre jar can suck the air and form bubbles inside when you pour the water from it?
Manova Aug 9, 2019 0 945
When you pour the water from a bottle making the bottle upside down the water comes out and there is a space created inside the bottle. That space has no air and it is called vacuum and the pressure of air is zero. Naturally, air flows from high pressure area to low pressure area automatically without any external force. Nature always tries to maintain a balance. So the outside air which is at one atmosphere pressure rushes inside the bottle to fill the space to balance the pressure. This forms the bubble and makes the water to come down slowly.
Manova Aug 5, 2019 0 749
The speed of any objects which fall on the earth when it is simply dropped from a certain height is same without any medium (without atmospheric air). So the objects will fall to the ground at the same time. When you drop a heavy metal ball and a feather from a certain height the heavy metal ball and the feather will fall to the ground at the same time without atmospheric air (in vacuum).
Manova Aug 1, 2019 0 747
Due to surface tension of the water on the surface the needle floats. Consider the water surface like an elastic rope. When a small object having less weight is kept on the rope the rope deforms down a little amount. In the same way when the needle is kept on the water surface it floats.
Manova Jul 24, 2019 0 755
While we drink the water through straw we suck the air inside the draw. While we suck it some air inside the draw comes up to our mouth and there is less amount of air inside the straw in more space. So the pressure of the air is decreased inside the straw. While there is a difference in pressure the atmosphere tries to balance it. So the air outside the straw which is at high pressure tries to enter into the straw and so it pushes the water on the surface of the container. This makes the water to go inside the straw.
The earthen pot contains small pores. The water tries to go out through this holes but it gets evaporates on the outer surface of the pot. For the water to change from its liquid to vapour state it needs energy. This energy is taken from the remaining water inside the earthen pot as heat energy. So the water inside the earthen pot gets cooled.
Manova Jul 19, 2019 0 1508
If the tea is poured in a plate the tea will be cooled fast. But if it is in glass then it will cool slowly. From this we can understand that the surface area of the tea is less in the glass and the surface area is more in the plate. So the heat transfer easily takes place where there is more surface area. So to increase the surface area we make the hot tea poured from higher distance to lower distance and the tea cools fast.
Manova Jul 11, 2019 0 2197
If there is no gap → When the material (railway track, concrete, steel, etc.) is heated it expands and when it is cooled it contracts. So the railway track or the bridge in summer season will be heated and so it tries to expand. So the track or the bridge will try to bend in different directions if there is no gap. But the track or the bridge in winter season will be cooled and so it tries to contracts. So the track or the bridge will try to straighten or separate themselves apart by cracking. If there is gap → When the railway track or the bridge tries to expand the gap is filled. When the railway track or the bridge tries to contract the gap is increased some more. Thus the railway track or the bridge stays in their original direction.
Manova Jul 10, 2019 0 2915
The outside atmospheric air always contains some water in the invisible state (Gaseous State). When the cool drink or cold water in the bottle cools the outside air, the outside air gives some water in the visible state (Liquid State). The water from the outside air stays at the outside of the bottle and looks like the bottle sweats.