**By Hafiful Hadi S**

**NIM RSA1C311018**

**Physics Education Student 2011**

1.

**In my diary life**

When playing the ball on the ground I was exhausted what if more kicking the ball your body will be more tired. as well as the ball kicked, when we kick the ball hard will be thrown farther. apparently felt fatigue caused by a change in the energy of the motion of the body into kinetic energy to the ball. This energy causes the ball was thrown or moved from one position to another position.

In physics, the energy possessed by a moving ball is called kinetic energy. Energy is the ability to do work. therefore when it is connected with the work in getting an equation:

Ek = 1/2 mv2

Ek = kinetic energy (J)

m = mass (kg)

v = velocity (m / s)

of the equation is known that the kinetic energy depend on mass and velocity

as the ball of mass m is thrown with a certain velocity, it has a kinetic energy, the greater the mass and velocity, the greater the kinetic energy in the possessed

A ball with a mass of 1 kg thrown with a speed of 2 m / s then the above equation the kinetic energy obtained was 2 j.

**My predicting**

What happens if a ball of mass m with an initial velocity in throwing on a rough floor, after a distance s beam is stopped. this means that the force experienced by the ball the opposite direction to

speed so that the ball is initially slowed and stopped. What about kinetic energy?

Wtot = ΔEk = ½ mv2 (final) - ½ mv2 (initial) where v final = 0

so,

Wtot = - ½ mv2

kinetic energy turns negative value indicates a reduction / deceleration kinetic energy.

**c**

**Conclusion**

Energy is the ability to do work. Kinetic energy is the energy possessed by a moving object, the amount depends on the mass and velocity of the object.

2.

**simple pendulum experiment**

calculate the period and frequency

calculate the period and frequency

**Theory**

**Pendulum**is load with a rope tied to a place where the rope in use is not stretched.

period is the time that is needed to make one round

T = t / n

T = period

t = time

n = many rounds

frequency is the time that it takes to make one round

f = n / t

f = frequency (hz)

n = many rounds

t = time (s)

relationship between period and frequency

T = 1 / f or f = 1 / T

**Tools and materials is needed**

1. stative

2. weight

3. thread

4. rule

5. stopwatch

6. paper

7. protractor

**The procedures**

1. prepare the tools mentioned above

2. pieces of thread that will be used throughout the 15 cm

3. tie one end of the

**pendulum**on a string and the other end tied to the stative

4. give small deviation (no more than 10 degrees) to the pendulum

5. swing the pendulum to swing 20 times

6. count and record the time required by the stopwatch

7. look at how many seconds the pendulum reaches its

**highest point**

8. count period by the equation T = t / n by ignoring

**friction forces**that occurs

9. count the frequency of the equation f = 1 / T

3.

**calculate electric current in the circuit series**

**Ohm's Law**

The flow of electric current in a circuit does not end in the electric appliance. but circle back to the current source. Basically electric appliance electric current is inhibited. The relationship between electric current, voltage, and resistance can be likened to water flowing in a channel. The relationship is better known as Ohm's law.

I = V / R or V = I. R

I = Current electricity (A)

V = voltage (volts)

R = Resistance (ohms)

**from the equation above we know that the current strength is proportional to the voltage and inversely proportional to the resistance**

or

voltage proportional to the current strength multiply resistance

or

voltage proportional to the current strength multiply resistance

Any current flowing through a conductor always have obstacles. If the electrical resistance is denoted by R. potential difference V, and a strong current I, the relationship between R, V, and I can mathematically be written:

**Kirchoff law**

The electrical current through a conductor can we view as the flow of river water. If the river is not branched, the amount of water at any place on the same river. So it is with an electric current.

The number of strong current into a branching point equal to the number of strong currents coming out of the branching point. The statement is often known as Kirchhoff's law because I was first presented by Kirchhoff.

So the equation is obtained:

I1 + I2 = I3 + I4 + I5

I get in = I out

or

T

**he electrical current**

**that goes in a circuit similar to the amount of current out**

**Series circuit**

According to Ohm's law: V = IR, the barriers are voltage V1 = IR1 R1 and R2 are the resistance voltage V2 = IR 2. Since the electric current flowing through the resistance R1 and R2 resistance, total voltage is VAC = IR1 + IR2.Series circuit

According to Ohm's law: V = IR, the barriers are voltage V1 = IR1 R1 and R2 are the resistance voltage V2 = IR 2. Since the electric current flowing through the resistance R1 and R2 resistance, total voltage is VAC = IR1 + IR2.

Given the total voltage VAC is a strong electric current flowing in the circuit as above (not branched chain) at every point the same then VAC = IR1 + IR2 I R1 = I (R1 + R2) R1 = R1 + R2; R1 = total resistance The circuit as above is called a series circuit. Furthermore, written R1 Rs (R series) so that Rs = R1 + R2 + ... + Rn, where n = the number of resistors. So, if some pieces are assembled in series resistance, resistance value increases. As a result, a strong current flowing vanishingly small. This is what causes lights to be less bright (slightly dimmed) if arranged in series. The more lights that are strung together in series, flame increasingly dim. If the lights go out (break), the other lights off.

**sample questions**

a series circuit consisting of R1 = 2 ohm R2 = 4 ohm, 8 ohm and R3 = R4 = 1 ohm with 2 volt voltage. specify

a. total circuit

b. Strong electrical currents

completion

a. to determine the total circuit of series circuit used formula

Rtot = R1 + R2 + R3 + R4

Rtot = 2 ohm + 4 ohm 0hm + 8 + 1 0hm

Rtot = 15 ohms

b. define strong electric current

I = V / R

I = 2 volts / 15 ohms

I = 0, 13 ampere

**we get that if voltage 2 volts and total resistance is 15 ohm. so that current electricty it is 0,13 ampere**

4.

Sound associated with the sense of hearing. imagine if the sound does not exist or is not able to hear the sense that the world would be so silent.

The sound is the result of a longitudinal wave vibration can stimulate the sense of hearing.

What is a longitudinal wave?

waves are vibrations that propagate either through the medium of an intermediary or not. longitudinal wave is a wave that requires a medium to propagate.

always sound waves need a medium intermediaries in the propagation and airborne sound.

as evidence that sound waves

1. Guitar string in quotes

guitar string in quotes will make the strings vibrate, the vibration that would arise from sound waves

2. Drums were beaten

when the drum in percussion drum causes the vibrational energy of the air particles around it vibrate follow drum vibration. then it was transferred to form the density and undensity in the air. if this wave to the human sense of hearing, there came the sound of drums before.

3. If you are in the vacuum we did not hear a sound.

while in the vacuum we would not be able to hear sounds at result that produced sound waves can not propagate so that the sound will not be heard or not up to the sense of hearing. This is evidence that the sound is a longitudinal wave.

because the sound is the sound waves possess the general properties of the wave

resonance, diffraction, reflection, refraction, and interference

The sound is the result of a longitudinal wave vibration can stimulate the sense of hearing.

What is a longitudinal wave?

waves are vibrations that propagate either through the medium of an intermediary or not. longitudinal wave is a wave that requires a medium to propagate.

always sound waves need a medium intermediaries in the propagation and airborne sound.

as evidence that sound waves

1. Guitar string in quotes

guitar string in quotes will make the strings vibrate, the vibration that would arise from sound waves

2. Drums were beaten

when the drum in percussion drum causes the vibrational energy of the air particles around it vibrate follow drum vibration. then it was transferred to form the density and undensity in the air. if this wave to the human sense of hearing, there came the sound of drums before.

3. If you are in the vacuum we did not hear a sound.

while in the vacuum we would not be able to hear sounds at result that produced sound waves can not propagate so that the sound will not be heard or not up to the sense of hearing. This is evidence that the sound is a longitudinal wave.

because the sound is the sound waves possess the general properties of the wave

resonance, diffraction, reflection, refraction, and interference