physic group by arianna menin https://padlet.com/menin_arianna01/kv60i6n8v78o Made by Arianna Menin, Cecilia Fiori, Nicole Cicalese and Federica bacchini. en-us 2018-02-01 12:39:13 UTC 2025-12-11 21:27:06 UTC hello@padlet.com https://padlet-assets.s3.amazonaws.com/icons/Bigthunderstorm.png hydrostatics, Density and Pressure menin_arianna01 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227029831
  • hydrostatic studies fluids at rest.
    • a fluid is a substance that can flow (liquids and aeriform substance are fluids).
    fluids can also conform to the boundaries of the container in which they are placed.
    • the density is the ratio of a mass af a substance and it's volume. 
       mass/volume= m/v
    the units of measurement are ks/m3
    the higher is the temperature of a substance the smaller is the density because the volume increases with the temperature.
    • the pressure is the magnitude F of a perpendicular force devided by the area S of the surface to which the force acts on.
       F(perpendicular)/s
    the units of measurement are N/m2=Pa (pascal)

    pressure is not a vector quantity but a scalar quantity.

    for a given P ressure, Force and Area are directly proportional.
     10N/1m2=10Pa.   20N/2m2=10Pa.

    while for a given Force, Pressure and Area are inversely proportional.
    10N/1m2=10Pa.     10N/2m2=5Pa

    and for a given Area, Pressure and Force are directly proportional.
    10N/1m2=10Pa.     20N/1m2=20Pa


    ]]>     2018-02-01 13:55:24 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227029831     7 experiments menin_arianna01 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227074905 during the lesson we saw 7 different experiments.
    1. plasticine in water.  Having two balls of the same weight the first thing to do is to change the shape of a ball making it become a discoid shape. putting the two balls in the water you will see that the first ball which has a spherical shape sinks, while the second one, that has a discoid shape, floats.
    2. Syringes with air. The first thing to do is to connect two syringes with a plastic tube and fill them of air before closing them with their pistons. pushing the piston of one syringe, you will see the one of the other syringe rise up and the same happens to the first piston, if you push the one of the other syringe.
    3.  syringes with coloured water. The first thing to do is to put the colour in a container full of water in order to colour it. pouring a bit of coloured water into the syringes and moving them up and down vertically, you will see the colour passing from one syringe to the other one when they are at the same height. 
    4. fish in the bottle.  Before starting, you have to fill the bottle of water and then put the fish into it. If you press the middle of the bottle, you will see that the fish goes down to the bottom while if you stop pressing it, the fish will go up to the top of the bottle. 
    5. bottle with two holes. Obtaing two holes (one above the other) and then cover them with two pieces of scotch. After filling the bottle of water, and having removed the pieces of scotch you will see that the water spreads out from the two holes not equally. from the hole at the top of the bottle the water spreads out slowly, while from the bottom one the water spreads out quickly. 
    6. Bottle with one hole . After piercing a water bottle one time and closing the hole with scotch, fill the bottle of water, close it with the cork and take off the piece of scotch. You will notice that the water doesn’t come out, instead if you also take off the cork the water will start spreading out from the hole.  
    7. Syringes with many holes.  The first thing to do is to pierce a syringe, making many holes and covering them with scotch. After that fill the syringe with water and take off the pieces of scotch. if you start pressing the piston of the syringe you will see that the water spreads out from all the holes at the same speed and in the same direction of the holes.
    ]]>     2018-02-01 15:04:13 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227074905     cecy122001 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227119092 LESSON 01/02/2018:
    ANSWERS:

     1.For a given force (weight), if I double the area of my shoes,  the pressure becomes the  half. So it’s easier to walk in a larger area.   
     2. For a given force (pressure), if I have a smaller surface the pressure applied is larger so I can cut better. 
    3. For a given force (force of my arm)  if I exert it on a smaller surface, I exert a bigger pressure.

    PASCAL’S PRINCIPLE:

    P1=P2
    F1/A1= F2/A2
    10= 10/1= 100/10=10
    ]]>     2018-02-01 16:12:11 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227119092     Pins and a balloon menin_arianna01 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227135255 For this experiment, we need:
    •  two balloons
    • some pins
    The first thing we have to do is inflate a balloon and tie it, then we take a pin and put the balloon on it. The balloons will of course pop.
    Now what we have to do is, inflate another balloon and tie it as we did for the first balloon. Then, we have to take a large number of pins and put them on a table with the sharp part facing the sky. Putting the balloon on the pins we notice that the balloon this time doesn't pop even if you press on it.
    From this we can conclude that when there is only one pin, since the pressure is high the balloon pops, but when there are a lot of pins the pressure is distributed in a larger area and so, since area and pressure are inversely proportional, every pin has a lower pressure and the balloon doesn't pop as the previous do.
    ]]>     2018-02-01 16:36:32 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/227135255     lesson 03/02/18 The Pascal and Stavin's Law menin_arianna01 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/229216515
  • The Pascal is an external force that push over a liquid.
  • Pascal's principle = any change in the pressure applied to a conpletly enclosed fluid is transmitted undiminished to all parts of the fluid and the enclosing walls.
    • a pascal's principle application is the hydraulic press.

    P1= F1/A1    =      P2=F2/A2
    A= pi  x  r2

    • STAVIN'S LAW
    the pressure at a point in a liquid at a static equilibrium depends only on the depth at that point.

    P=Po(atmospheric pressure) + g (gravity) x d (density) x h (height)

    examples of stavin's law application : trapezoidal shapes in dams and swimming pools


    ]]>     2018-02-07 17:24:59 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/229216515     Buoyancy and answers menin_arianna01 https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/230251530 The Buoyancy (B) equals to the wait of the fluid displaced that as to be at least equal to the wait of the object.
    B= m x g = v x g
    if an object float the wait is equal to the buoyancy.
    an object can float only when the density is less than the fluid.
    answers
    n.2=ships floats thanks to buoyancy.
    any object can float or sink based on his density.
    if ut is more dense than the fluid, it will sink, while if it is less dense than water it will float.
    the basic rule is that an object will sink if it weight more than the volume of the water.
    when something is resting in or on water, it feels an upward (buoyant) force equal to the weight of the water that it pushes aside (or displaces). If an object is completely submerged, this buoyant force, pushing upwards, effectively reduces its weight: it seems to weigh less when it's underwater than it does if it were on dry land.]]>     2018-02-10 09:14:20 UTC https://padlet.com/menin_arianna01/kv60i6n8v78o/wish/230251530