Third Practice

PROCEDURE

1. First we make 2 holes in a recipient of 1 lt
2. We filled it with water we observe what happen and measure the distance of the water that goes out
3. Then we connect the hair dryer
4. And put on the top of it a ping pong ball and observe what happen
5. After that we put 2 cans together in an horizontal way over the table
6. Finally we blow between the 2 cans and observe the raction of them

QUESTIONS

•Bernolli'principle: as the velocity of a fluid increase ,the pressure exerted by the fluid decreases

•Describe what you saw: We make holes in a recipient with water, in the hole that was near the base of the recipiente the water get out slower than in the one that was at the top

•What happen with the ping pong ball? When we take on the hair dryer the ball goes up so it start to float

•What happen this with the ping pong ball? Because of the air exerted by the hair dryer that blows in an upward direction because of the position of the dryer.


•What happen with the cans? We put the cans together and when we exhale between them they join instead of spread 

•Why happen this with the cans? The air sorrounding the can exerts a pressure and force equal in all directions by blowing between the cans, air preassure decreases in this region and the sorrounding stationary air cans exerts greatre preassure cans pushing against each other

 

Second Practice 17/02/11

Practice 2
Density


The mass density or density of a material is defined as its mass per unit volume.The symbol most often used for density is ρ. density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight. Different materials usually have different densities

Objective: obtain the density of different substances using only 10ml of each one

Material:

·         Water

·         Lechera

·         Oil

·         Test tube

Procedure:

1.       Put the test tube in the balance to obtain its mass

2.       Pour in each test tube 10ml of each substance

3.       Put again the test tube in the balance to obtain its mass now that it has the substance

4.       Then substract the mass of the test tube to the obtained mass of the test tube with a substance

5.       Now with the mass and the volume, apply density formule (p=m/v) and calculate the density of each substance  

Results:

·         Water

m= 10g

v= 10ml = 10cm3

ρ= 1g/cm3

·         Oil

m= 9g

v= 10ml = 10cm3

ρ= 0.9g/cm3

·         Lechera

m= 14.9 g

v=10ml = 10cm3

ρ=1.47g/cm3

First Practice 10/02/11

Objective=  know the densitity  of  cubes each one made up of different materials

Materials:

·         Cubes of: wood, cube L, cube E, cube P, cube A

·          balance

Procedure:

1.       Measure each side of the cube

2.       Obtain the volume of each cube

3.       Put the cube in the balance to obtain its mass

4.       After getting the mass applied the formule of density

5.       Obtain the density of each cube

Results:

·         Cube L:

m=11g

v=1.33cm
ρ=8.27 g/cm3

·        
    Cube wood:

m= 0.5g

v= 1cm3
ρ=0.5 g/cm3

·        
     Cube E:

m=13.3g

v= 1.45cm3
ρ= : 9.17 g/cm3

·        
    Cube P:

m=13.9g

v=1.33cm3
ρ=10.45 g/cm3

·        
     Cube A:

m=3.5g

v=1.33cm3
ρ= 2.6 g/cm3

Materials of cubes:
 wood
cupper
steel