Lab Report "FREE FALL"

Title:       "FREE FALL - Altitude vs Energy"

Investigation question: 

¿How does the altitude within a marble is dropped, affects the impact it does on a jelly like substance?

If we throw a marble from a specific altitude, how will it affect the depth of a jelly like substance inside a beaker located on the floor, when the ball hits it.

Objective:

Our objective throughout this whole experiment has been to observe and conclude how depending on the height from which we throw, in our case a marble, affected the depth of a jelly like substance. Our goal is to see the different impacts - how deep the marble goes- whilst thrown from different altitudes.

Background Information:

When we talk about free fall we must talk about it relating it to Isaac Newton, who discovered gravity because of the free fall of an apple right to his head. Therefore free fall is any motion a body in which gravity is the only force acting against it. Objects that goes under free fall, are not facing a significant air resistance; they are because of gravity.

             

                   

When an object falls through air, it usually faces air resistance. Air resistance is the result of collisions of the object's main surface with air molecules. The actual amount of air resistance faced by the object depends on a large variety of factors.

The two most common factors that have a direct effect against the amount of air resistance are;

1.- The speed of the object.

2.- The cross-sectional area of the object.

In which we can say that "Increased speeds result in an increased amount of air resistance. Increased cross-sectional areas result in an increased amount of air resistance".

           

Throughtout free fall, potential energy takes place. Potential energy is the one stored in an object or individual, its SI unit is joules (J). Potential energy refers to the equation of P.E= mass multiplied by the gravitational force - natural feature by which all physical bodies are attracted to each other- multiplied by the height.

             


m= mass of the object

g = gravitational force (9,8 m/s2)

h= Height


Hyphotesis:

The height from where the marble is thrown will affect the jelly like substance, to where it is thrown, as the marble hits its with more potential energy, if the altitude is higher, while if we throw the marble from a smaller altitude onto the substance, the marble will hit it with less energy. This is due to the formula of potential energy where Ep=mass x gravity x height, so when the height is increased, the velocity increases as it takes more time to reach the floor (as the mass of the marble and gravity always stays the same in this experiment), and due to the increase in the velocity, the energy will also increase, due to the formula already mentioned. These variables are directly proporional because as the height of the marble increases also the energy, and finally also the depth of the hole created during the impact.

Variables:

Independent variable: the height will be changed during the experiment, so that we can obtain the different data and prove that the hypothesis is correct. The different heights will be 0.5, 1, 1.5, 2, 2.5 m and I will measure them using a metre.

Dependent variable: the energy with which the marble will hit thejelly like substance, will change during the experiment and we will measure it by seeing how much has it decreased, when the marble hits it at every altitude so that we can obtain the different data and prove that the hypothesis is correct. The jelly like substance will decrease its depth, as when the marble is thrown from different altitudes, the energy also changes, so there will be different amounts of energy if you throw the ball from 0.5 m than for 2 m. Due to the changes in the energy, the marble will hit harder or softer the substance, so when the marble hits the substance harder, it will decrease more than when if it hits it softer. I will measure the decrease of the depth of jelly like substance using a ruler, as it will only decrease a few centimeters.

Controlled variables: the material and the shape of the marble will be kept the same during all the experiment, as I will always use the same marble and I will measure its weight each times it falls to the floor, so that I can keep both factors constant. The density of the jelly like substance will be kept constant during the experiment, so that it not affects how deep the marble goes when throwing it from different altitudes. The pressure, the wind and the length from where the object is thrown will be kept constant so that they don’t affect to the free fall of the object, by throwing the object in a closed area where there isn’t any wind, and using a pressure sensor to control the pressure in the atmosphere.

Materials:

- Marble

- Jelly like substance

- Ruler

- Beaker

- Meter

- Computer

(Jelly like substance measures, 0,5 liters beaker and 2 measurements of Sodium Polyacrylate)

Procedure

1. Colocate the jelly like substance inside a beaker. 
2. Introduce a ruler of 50 cm inside the beaker with the jelly like substance to measure how deep the marble goes.
3. Be sure that the surface of the substance is completely smooth and without any lumps so that the marble always hits a straight surface which would not alter the experiment. 
4. Throw a marble from 0.5 m of altitude using a meter, onto the substance and calculate how much depth has it decreased. 
5. After colocating the jelly like substance correctly inside the beaker, without any holes inside it or lumps on its surface, repeat this process but with different altitudes; 1, 1.5, 2, 2.5 m. 
6. With the data obtained, perform a table and a graph, on how the depth of the jelly like substance has varied, every time that the mable has been thrown onto it at different altitudes.

Data

The altitude in meters from where the marble is thrown, the depth of the hole in cm created by the marble when hitting the jelly-like substance and the average of the depth of the hole in cm from the five data obtained from each altitude.

Altitude (m)	Hole (cm)					Average (cm)
0,5	3,5	2,3	2,5	3	3,2	2,90
1	4,3	4,6	4,3	4,5	4,1	4,36
1,5	5,3	5,2	5,4	5,3	5,7	5,38
2	6,1	6,2	6,8	6,5	6,3	6,38
2,5	7,5	8,1	7,2	7,8	7,4	7,60

   



 

 





Bibliography

1. Fall, W. (2014). Fluid dynamics - water pressure in free fall - physics stack exchange. [online] Retrieved from: http://physics.stackexchange.com/questions/4619/water-pressure-in-free-fall [Accessed: 23 Jan 2014].

2. Physicsclassroom.com. (2014). Free fall and air resistance. [online] Retrieved from: http://www.physicsclassroom.com/class/newtlaws/u2l3e.cfm [Accessed: 23 Jan 2014].

3. Wikipedia. (2014). Free fall. [online] Retrieved from: http://en.wikipedia.org/wiki/Free_fall [Accessed: 23 Jan 2014].

4. Wikipedia. (2014). Equations for a falling body. [online] Retrieved from: http://en.wikipedia.org/wiki/Equations_for_a_falling_body [Accessed: 23 Jan 2014].