Final exam Second Task : Describe an Experiment

Friction Force

Basic Theory : 

Try pushing a cardboard box on the floor! When you push the cardboard there is  friction between the surface of the cardboard box and the floor. The frictional force will hinder the movement of cardboard. The power of resistance due to friction is called friction. Thus, friction is a force that causes resistance when two surfaces touch each other.

equipment : 

-surfboard  

-marbles  

-HVS

-fabric

-sandpaper 

-playdough

-carton  

-sand

A. goal of experiment : Comparing the movement of objects on different types of surfaces.

Procedureof experiment :

1) Prepare a skateboard
2) Launch marbles on top of the sled. Observe the movement of marbles being rolled
3) Cover the cardboard sled. Observe the movement of marbles being rolled
4) Cover with sand sled. Observe the movement of marbles being rolled
5) Cover with a cloth sled. Observe the movement of marbles being rolled
6) Cover sled with sandpaper. Observe the movement of marbles being rolled
7) Record the results of observations

B. Goal of experiment : Enlarging and reducing the frictional force

Procedure of experiment :

 
1) Prepare a skateboard
2) Launch marbles on a skateboard. Observe the movement of marbles being rolled
3) Wrap marbles using paper and then launched. Observe and record your observations
4) Launch a cube-shaped dough on a skateboard. Observe the movement of the clay is rolled
5) Change the shape dough into a round and then launch. Observe and record observations

Final exam Forth Task : Sound as Wave Essay

Have you ever thought why our ears can hear? it is because sound as waves. previously let's see what is actually wave. wave is a disturbance or vibrations that propagate. then why sound as can be described as wave? because sound is longitudianal wave, that is wave that propagate to the direction of vibrate in the direction of propagation direction. When a sound source vibrates, sound waves propagate through vibrate air molecules with the way - air molecules back and forth. Making every moment, these molecules were squeezed in some places, they produce high-pressure region, but in other places stretched, resulting in the pressure region lower. High and low pressure waves alternately moving in the air, spreading from the sound source. That's why sound waves are longitudinal waves.

The sound is one of mechanic wave and therefore we find it anywhere, as long as it is contained in the air, water or solids. But when we observe a vibrating sound source in space vacuum, then we will not hear a sound as we hear on earth .

Most of sound is a combination of various signals, but the pure sound could theoretically be explained by the speed of vibrate or frequency is measured in Hertz (Hz). The frequency of the number of wave that occur in one second. Single sound frequency regularly called tone, whereas a single sound is called irregular frequency hiss. Limit the frequency of sound that can be heard by the human ear roughly from 20 Hz to 20 kHz in common amplitude with variations in the response curve. Sounds above 20 kHz is called ultrasonic and below 20 Hz is called infrasound. Ultrasonic and infrasonic sound can not be heard by humans but some animals can hear sounds with frequencies. for example bats and dolphins can hear the ultrasonic frequency while the frequency infrasonic sound can be heard by dogs and crickets.

Final exam Third Task : Calculating About Electrical

The Electric Field

The electric field is defined as the space around an electric charge source where other electrical charge in this space will experience coulomb force or electric force in the form of pull or repulsion.

Charged objects that generate an electric field we call the charge source. Another charge that we put under the influence of an electric field the charge source we call the test charge. Powerful electric field at the location where the test charge is defined as the Coulomb force (electric force) acting on the test charge divided by the test charge, or it can also be said that the electric field strength is directly proportional to force and inversely proportional coulomb big test charge.

For example:

Calculate the electric field strength experienced by the test charge by 9 by Coulomb electric force of 360 Newton!

"Electric field strength is directly proportional to force and inversely proportional coulomb big test charge."

Strong electric fields in the above situation is the electric force of 360 Newton is divided by the test charge equal to 9 Coulomb . so the results obtained is equal to 40 Newton per  Coulomb.

Final exam first task : kinetic energy report

kinetic energy
Hello all, how are you? on post this time I will invite you to discuss the kinetic energy. you must have heard about kinetic energy, well so what is the kinetic energy??
Kinetic energy is the energy possessed by moving objects.
Kinetic energy of an object is defined as the effort required to move an object with a given mass from rest to reach a certain speed. Kinetic energy is divided into two translational kinetic energy and rotational kinetic energy.
First we will discuss about the translational kinetic energy .translational kinetic energy (KE) is the energy possessed by a moving object straight. 

I once played marbels, first I put a marble at a point that we consider point A then I have pushed it so marbel marbel move straight and had stopped at point B. When the marble was being moved from point A to point B, he has a kinetic energy proportional to its mass and the square of the velocity.
so if we assume that the mass of marble is 0.2 kg and its speed is 0.1 m / s ^ 2 we can determine the kinetic energy possessed by the marble using the equation: KE = 1/2 m v ^ 2 

so that we have the result is 0,001 joules. 

 

Now we will discuss about the rotational kinetic energy.
rotational kinetic energy is the energy possessed by objects that perform rotational motion.

 
one time I ever rode a bike from my house to the store. My wheels have being doing
rotational motion so that they have a rotational kinetic energy.

we can determine the amount of rotational kinetic energy by using the equation:
ER = 1/2 I w ^ 2

or we can say rotational kinetic energy is proportional with moment inertia and its angular velocity.

so if we assume that the moment of inertia wheel my bike is 0.8 and the angular velocity is 15 rad / s ^ 2, using the equation above we can see that the rotational kinetic energy carried by the wheels of my bike is at 90 joules.

Capilarity

Capillarity is the event rise or fall on the liquid surface of the capillary tube, as shown in Figure 1.1 In the picture, the inside diameter of the capillary tube from left to right are getting smaller. If the diameter of the capillary tube degrease , the water level rise in the capillary tube will be increase .

Figure 1.1 capillary tube

The surface liquid that wetting  the wall , such as water, will rise. And while it does not wet the walls, such as mercury, will go down. In everyday life, examples of capillary phenomenon are as follows.  kerosene up through the wick in the kerosene lamps or kerosene stove,  wet walls during the rainy season, water in the soil up through the timber vessels.

kerosene lamps

kerosene stove

wetting wall by water events, or mercury does not wet the wall can be explained by considering the attractive force among particles . The force of attraction is called cohesion if among particles are similar, while attractive forces are not similar in the among particles called adhesion. Water soaks glass wall due to the cohesive forces of water antarpartikel smaller than the adhesion force between water particles and particles of glass walls. Meanwhile, mercury has a cohesive forces greater than the adhesion force with a glass wall so it does not wet the glass wall. Adhesion force of water greater than the cohesion of the water causes the meniscus-shaped concave, while the force is greater than the cohesion of mercury causing surface adhesion force mercury meniscus convex shape. If the liquid is inserted into a capillary tube, a liquid surface will be curved. Curved surface of liquid in the pipe is called the meniscus.

Figure 1.2 y force of surface tension on the fluid in the capillary tube. Fluid rises if θ <90 ° and down if θ> 90 °.

Figure 1.2 shows the surface tension force of  fluid in the capillary tube. Shape of the surface liquid in a capillary tube depends on the contact angle (θ) fluid. The surface of the liquid will rise if θ < 90 ° and down if θ> 90 °. Increase or decrease the liquid surface can be determined by the following equation.

mg = F cosθ

Vg = ρ cosθ γ l

r2hg ρ π = γ 2π r cosθ

by:
h = increase or decrease in liquid (m),

γ = surface tension (N / m),

g = acceleration due to gravity (m/s2), and

r = radius of base tube / pipe (m).

If a liquid wetting the pipe wall, the contact angle of less than 90 ° and the liquid rises until it reaches the equilibrium height. Contaminants are added to the liquid will change the angle of contact, such as detergents alter the magnitude of the contact angle greater than 90 ° is smaller than 90 °. In contrast, substances that make waterproof fabric (waterproof) causes the contact angle of water with the cloth becomes larger than 90 °.

Calculating Work

In physics work done by a force is defined as the product of the force with which the direction of movement of the object style.
Can be formulated:   W = F . s

Work units in SI is joule. One joule is the magnitude of work done by force of one newton to move an object in same direction as force as far as one meter.
Relation work and energy is the magnitude of work done by a force in the process is the same as much as energy transferred.

Several work done by force
If the work done by first person and second person to move an object to the right as far as s is

W1 = F1 s (*) and W2 = F2 s (**)

It is known that the resultant of two force in same direction is F = F1 + F2, so the total work made ​​by two person were

W = F s, W = (F1 + F2) s

By entering F1 s = W1 (see *) and F2 s = W2 (see **), it is obtained

W = W1 + W2

In general it can be concluded as follows:
The work done by the resultant forces in same direction and the opposite direction, which causes it to move an object as far as s, equal to the amount of work by each force.

Magnetic Field

Magnets is an object that has a magnetic field. The word magnet is derived from the Greek magnítis lithos meaning stone  magnesian. Magnesia is the name of a region in Greece in the past are now called Manisa (now located in Turkey) which contained lodestone discovered since ancient times in the region.

magnetic field is the area around maget influenced by magnetic force

in the earth there are some place which have magneric field like Jabal Magnet in Madinah .
Now we will see what is the magnetic field actually from 3 dimension magneric field experiment .

3 Dimension Magneric Feld Experiment

prepare:
Plastic bottles, white oil, iron sand, hexagonal or triangular magnets, small spoon

Step Event:
Fill a plastic bottle with a white oil until the neck
Put a little sand iron. Replace the bottle cap tightly
Shake the bottle and hold the bottle against the wall magnet

observe:
Iron sand forming a distinctive pattern

explanation:
Each magnet pick-shaped magnetic field lines of magnetic force. White oil is useful to slow motion  of the iron sand so that the iron sand does not directly fall to the bottom of the bottle after shaken and allowed to be withdrawn magnets to form the lines of magnetic force.