UJIAN SEMESTER

ANSWERED

              1.      In general, the kinetic energy is the energy that belongs to an object that is moving. Specifically, the kinetic energy is the energy that belongs to a body of mass m is moving with a speed of (velocity)V.

Every moving object has energy. The energy possessed by a moving object is called kinetic energy. Or just Review: Kinetic energy is the energy that is being done on a moving object.
There are two types of classification based on kinetic energy, they are:
1. kinetic translation
translational kinetic energy is the energy possessed by a moving object on a straight track
2. Rotational kinetic.
If the translational kinetic energy is the energy is owned by an object moving in a straight line, rotational kinetic energy is the energy possessed by objects that perform a circular motion.

The experiment this time I took the example of translational kinetic energy in the daily life.
One case or the event about kinetic energy in the daily life is that I did experiment a simple kinetic energy is a small piece of paper and a stone I drop to the floor simultaneously. Based on the experiments that I did. Apparently a stone has kinetic energy greater than the small piece of paper. This is evident from the speed of the stone first strike the ground or the floor compared to the small piece of paper.
Based on the results of experiments that I do, I can analyze the object that has a great future will have a greater kinetic energy. And conversely if the mass is small then small kinetic energy.
So, the conclusion the greater the mass of an object the greater the kinetic energy. The faster the object moves, the greater the kinetic energy as well. The magnitude of the kinetic energy of an object is determined by the mass and velocity of motion. Relationship between body mass (m), velocity (v), and the kinetic energy (Ek) written mathematically in the following formula.

Description:
m                     : mass (kg)
v                      : velocity (m / s)
EK                   : kinetic energy (Joule)

After that, based on the formula above we can calculate the kinetic energy of an object that has mass and velocity using the formula above. Then we can take the example problems as follows:

  A bike whose mass is 40 kg moving with a speed of 10 m / s. Determine the kinetic energy of the bike!

Known :

m         :  40 kg

v          : 10 m/s

ask       : EK ?
discussion :
The kinetic energy of an object:
Ek = 1/2 m v2
Ek = 1/2 x 40 x 10^2
Ek = 2000 joules

Experiments We Do Next After We Can Predict The Kinetic Energy Of An Object In An Unknown Time And The Speed Of The Object.
Okay Good Luck Physics Experiments :)

 

   2. Experiment To Calculate The Acceleration Of Gravity By Pendulum

At this time I would do to calculate and prove the acceleration of gravity. Is it true that the value of gravity is 9.8 m/s2 by using simple pendulum experiment

To determine the Earth's gravity to do a simple pendulum swing experiment,
with simple equipment. By observing the harmonic motion of a pendulum that has
maxima deviation of 15 degrees. And with menentukkan time required for 10
vibration with a long rope that is different. Then the calculated value corresponding gravity
with the following equation:

o   Tools and Materials:
string

Stopwatch 1 piece
Pendulum
arc
paper
Stationery

ü  Procedure :

a.       Prepare All Experimental Materials Such As Yarn, Pendulum, Stopwatch, Paper, Bow And Stand.

b.       Pendulum With A String Bind. 
c.        Swinging A Pendulum At An Angle Of 15 Degrees, Do Not Use The Highest Point On The Pendulum.

d.      Calculate The Time Required For 10 Vibrations Ignoring Air Friction Force.

e.       Record The Time Indicated By The Stopwatch.

f.       Observe Pendulum And Summarize The Data Obtained.

            3.  COULOMB FORCE OR ELECTRIC FORCE

We have already know that two similar charges attract each other and the two are not similar charges will repel. When it was junior high school class IX, knowledge is not enough. We also need to know how large a force of attraction and repulsion how-reject.
Charles Augustin de Coulomb was the first to examine the relationship with the two charge electric force and the distance between them by using a torsion balance. In that study ultimately concludes Coulumb in a law called the law of Coulumb:
Large Repulsion Or Attraction Force Between Two Electrically Charged Objects, Proportional To The The Respective Electric Charge And Inversely Proportional To The Square Of The Distance Between The Two Charged Objects.

The force of attraction or repulsion reject is called the Coulomb force or electric force.
Mathematically, Coulomb's law can be formulated:

Description:
F = force of attraction or repulsion (Newton)
k = constant = 9 × 109 N m2 C-2
q1, q2 = charge of each object (Coulomb)
r = distance between the two objects (meters)

Example:
1. Two charges each 2μ + C and 3μ + C , separated by 2 cm. If k = 9 x10^9 N m2/C2, how much repulsion-reject?
completion
Given:
k == 9109 N m2/C2
Q1 = 2μ + C = 2106 C
Q2 = 3μ + C = 3106 C
r = 2 cm = 2.10-2 m
Asked: F?
Answer:

                                                      F = k. Q1xQ2/r^2 

 

 

= 13,5. 10^9-6-6-(-4)

= 13,5. 10¹

= 135 N

 Three point charges lie on the x axis; q1 = 25 nC at the origin, q2 = -10 nC is at x = 2m, and qo = 20 nC is at x = 3.5 m. Determine the net force on q1 and q2 qo result.
completion:
Third charge can be described as follows: 

F₁₀ = k = 9×10⁹ = 0,367 μN
F₂₀ = k = 9×10⁹ = - 0,799 μN

4       SOUND AS WAVE 

In physics, sound is a longitudinal wave is a wave form. longitudinal wave is a type of wave that propagates through a medium, which is produced by mechanical vibration and is the result of energy propagation. Sound source is also a source of vibration emits longitudinal waves in all directions through the medium of either solid, liquid or gas. Vibration source can be derived from the string / wire, pipe organ, even the waves on the beach.
Most of the sound is a combination of various signals, but the pure sound could theoretically be explained by the speed of vibration or frequency is measured in Hertz (Hz). Single sound frequency regularly called tone, whereas a single sound is called irregular frequency hiss. The amplitude of the wave of strong-weak determining a sound or loudness of the sound with a measurement in decibels (dB). The higher amplitudoya louder sound. For example, the sound of planes taking off approximately 120 dB. Medium leaves murmur about 33 dB.
Humans can hear sounds when sound waves propagate through the air or another medium to the human eardrum. Sound wave is a longitudinal wave causes the air molecules do not propagate but vibrate back and forth. Each time, these molecules are squeezed in some places, resulting in high pressure areas, but in other places stretched, resulting in a low pressure area. High and low pressure waves alternately moving in the air, spreading from the sound source. That's why sound waves can be described as longitudinal waves.
Limit the frequency of sound that can be heard by the human ear roughly from 20 Hz to 20 kHz in common with amplitude variations in the response curve. Sounds above 20 kHz is called ultrasonic and below 20 Hz is called infrasound.
The sound waves have symptoms such as interference, reflection, refraction and diffraction. The sound is a mechanical wave because it can propagate through a medium (solid, liquid or gas) and can not propagate in a vacuum.

The evidence and exempifying:

1   1.  Sound waves are longitudinal waves
Some aspects of the sound:
 The sound produced by a sound source is vibrating objects.
    From the sound source of energy transferred in all directions in the form of waves that longitudinal waves
   Sound waves require a medium / intermediate substance (solid, liquid and gas) and the sound can be detected by the ear or a tool.    

                2.   Vibrating source that can produce sound by frequency can be divided into:
    Regional frequencies less than 20 Hz are called infrasound frequencies.
    Regional frequency 20-20000 Hz called the area of ​​audio, can be captured by the normal human ear.
    Frequency area more than 20000 Hz are called ultrasonic frequencies.

3.  From the sound source can be up to our ears because the sound propagates as a longitudinal wave in the form of density and strain of medium molecules in its path.
Since sound is a wave, it can indicate the general properties such as wave interference, reflection, refraction etc..