1. Kinetic Energy
Kinetic energy is energy that a motion object.
Energy that objects similar to the work done by the force acting on
the object to change the object
from being still to a state of motion.
The kinetic energy there are 2, that are :
- Translational kinetic
energy is the energy owned by
objects that motion on a straight track
- Kinetic rotational energy is the energy owned by objects that do rotational motion.
- Kinetic rotational energy is the energy owned by objects that do rotational motion.
Okay
I observed
a door in my
house, when we pushed open the door, the door also rotates or rotating on
an axis. The hinge that connects
the door to the wall
serves as the axis of rotation. and when
the door is rotates door edges motion faster or
more speed. Instead
part door near
the hinges to motion more slowly
or less velocity.
So when an object rotates, the velocity (v)
of each particle is different, depending on the distance from the axis of rotation. Because each particle has
a mass (m) and velocity (v)
then we can say that when a rigid rotates, the
particles that make up all matter has a kinetic
energy of translational kinetic
energy, and the total kinetic energy of all the particles that make the same rigid kinetic energy of rigid. Mathematically it can be written :
And
in my
observation happens rotational
kinetic energy. Unit of kinetic energy is the joule,
the same as other forms of energy.
The kinetic energy is usually dependent on the mass and
velocity, but the rotational kinetic energy is dependent by the moment
of inertia and angular velocity.
Problem solving :
The
door rotates
on its axis with a moment of inertia of 0.15 Nm and angular velocity
of 10 rad /
s. How Ek rotation ?
Known : I = 0,15 Nm
ω = 10 rad/s
Ek = ½ I ω
= ½ .
0,15 Nm . 10 rad/s
= 0,75
Joule
so we can assume that if the moment of inertia of a rotating door of 0.15 Nm and angular velocity 10 rad / s the kinetic energy of rotation is 0.75 joule.
2. Frictional force
Friction is the force directed against
the direction of motion of objects or inclination
objects will motion. Frictional forces appear when two objects come
into contact. Large friction
force depends on the rough and smooth
surfaces friction against each other. Rough surfaces will cause friction force is relatively larger than a smoother surface, the
friction force is dependent object
weight but not
object surface area is dependent.
static friction force
Static friction is friction between two
solid objects that are not moving
relative to each other. As an example, static
friction can prevent object sliding down the
incline. The coefficient of static friction is
generally denoted by μs, and generally larger than the coefficient of kinetic friction.
Static friction resulting from a force that is applied just before the object is moving. The maximum frictional force between two surfaces before the movement is the result of the static friction coefficient multiplied by the normal force Fn f = μs. When no movement occurs, frictional forces can have a value of zero to the maximum friction. Each style is smaller than the maximum friction force trying to move one of the objects will be countered by the force of friction is equal to the force but opposite direction. Any force larger than the maximum friction will cause the movement occurs. Once movement occurs, static friction force can no longer be used to describe the kinetics of object, making use of kinetic friction.
Static friction resulting from a force that is applied just before the object is moving. The maximum frictional force between two surfaces before the movement is the result of the static friction coefficient multiplied by the normal force Fn f = μs. When no movement occurs, frictional forces can have a value of zero to the maximum friction. Each style is smaller than the maximum friction force trying to move one of the objects will be countered by the force of friction is equal to the force but opposite direction. Any force larger than the maximum friction will cause the movement occurs. Once movement occurs, static friction force can no longer be used to describe the kinetics of object, making use of kinetic friction.
Kinetic friction force
Kinetic friction (or dynamic) occurs when two objects move relative to each
other and friction each other. The coefficient of kinetic friction is generally
denoted by μk and generally always smaller than the static friction for the
same materials
Types of friction
There are two kinds of friction between two solid objects together moving forwards, the static friction and kinetic friction, which differentiated between the touch points between the two surfaces that remain or are changing (shifting). For objects that can be rolled, there is also another type of friction is called rolling friction (rolling friction). For a rotating object perpendicular to the surface or air-spin, there is also friction spin (spin friction). Frictional forces between the solid and the fluid is called the Carioles force-Stokes or viscous force (viscous force).
Types of friction
There are two kinds of friction between two solid objects together moving forwards, the static friction and kinetic friction, which differentiated between the touch points between the two surfaces that remain or are changing (shifting). For objects that can be rolled, there is also another type of friction is called rolling friction (rolling friction). For a rotating object perpendicular to the surface or air-spin, there is also friction spin (spin friction). Frictional forces between the solid and the fluid is called the Carioles force-Stokes or viscous force (viscous force).
Frictional
force advantage
and disadvantage
Examples of advantage friction force:
a. Footwear shoes and sandals made of rubber and the like, and form is such that if used will resist use in order not to slip.
b. Car tires, bicycle tires and motorcycle tires are made of rubber and form in design so that zoom in friction between the tire with road was also made rough.
Examples of disadvantage friction force:
a. Gir wheel and chain on the bike and a motorcycle or other parts that are friction can wear and damage. work reduce this friction can provide oil as a lubricant
b. In the car, motorcycle, or machines in the factory is always friction between the parts of the machine that quickly wear out or damaged. work reduce the this friction can provide oil as a lubricant.
purpose:
a. Determine the coefficient of static friction and kinetic coefficient of friction of the two surfaces
b. Determine the speed and acceleration of the motion on an inclined plane
Examples of advantage friction force:
a. Footwear shoes and sandals made of rubber and the like, and form is such that if used will resist use in order not to slip.
b. Car tires, bicycle tires and motorcycle tires are made of rubber and form in design so that zoom in friction between the tire with road was also made rough.
Examples of disadvantage friction force:
a. Gir wheel and chain on the bike and a motorcycle or other parts that are friction can wear and damage. work reduce this friction can provide oil as a lubricant
b. In the car, motorcycle, or machines in the factory is always friction between the parts of the machine that quickly wear out or damaged. work reduce the this friction can provide oil as a lubricant.
purpose:
a. Determine the coefficient of static friction and kinetic coefficient of friction of the two surfaces
b. Determine the speed and acceleration of the motion on an inclined plane
-
The coefficient of static friction coefficient of
friction between the
two surfaces collide silent.
-
The coefficient of kinetic friction:
the friction coefficient of the objects that collide
in which objects move
relative to one another.
The coefficient of friction arises
because of the combination of two
surface therefore the friction force vector
is always painting on the surface of the meet.
Tools and materials:
1. surfboard
2. block of wood
3. ruler measuring
4. stopwatch
1. surfboard
2. block of wood
3. ruler measuring
4. stopwatch
Procedures:
* Determine the coefficient of static friction
1. Put a block of wood on surfboard
2. Slowly lift surfboard until block reaches a position where the block will move right. Stop lifting and hold the surfboard in position.
3. Measure the price of x and h. Enter the data field
4. Repeat steps 1,2 and 3 with prices of different x
5. Calculate the coefficient of static friction
* Determine the coefficient of kinetic friction
1. Put a block of wood on surfboard
2. Slowly raise and stop the surfboard from sliding block current at the time and stop the stopwatch turn right when block reaches the end of the surfboard. Record the time in the field of data
3. Measure the distance x, h, and s in that position and record the data field
4. Repeat steps 1,2 and 3 with different price x
5. Calculate the coefficient of kinetic friction it
3. Calculating Electrical of resistance circuit
In
generally, circuits resistance classified into
circuit of series resistance, parallel
resistance, or a combination of
both. To create a series or parallel resistance
circuit a minimum of two resistance. Meanwhile,
to make a circuit
series-parallel combination of resistance required at
least three resistance. The types of circuit resistance
has its own advantages and disadvantages
of each.
Series circuit
The circuit
is one of the series
circuit are arranged on equal footing (series). Two or more resistance are arranged
in a sequence called the series resistance. Resistance in series to form an
electrical circuit is not branched. current flowing at any point of the same
magnitude. The purpose circuit series resistance to increase the value of
electrical resistance and dividing the potential difference of the voltage
source. The circuit resistance can be replaced with a series of resistance
called substitute series resistance (Rs).
Parallel circuit
Parallel
The circuit is one electrical circuit arranged lined up (parallel). Two or more
resistance are arranged side by side called parallel resistance. resistance are
arranged parallel to form electrical circuits branched and have more than one
lane of electric current. Arrangement of parallel resistance can be replaced
with a resistance called substitute resistance parallel (Rp).
Series circuit - Parallel of Resistor (Mixed)
circuit
mix is a combination of resistor series circuit with resistor parallel circuit.
mixed circuit is a circuit that is
composed of a series circuit and
parallel circuit in a single circuit for example, look at the picture.
Problem solving :
What is the total R value of a circuit mixed ((R1 + R2) / / R3) + R4 ?
Known :
R1
= 3 ohm
R2
= 3 ohm
R3
= 6 ohm
R4
= 7 ohm
Answer :
Rs = R1 + R2
Rs = R1 + R2
=
3 ohm
+ 3 ohm
=
6 ohm
1/Rp = 1/Rs + 1/R3
1/Rp = 1/Rs + 1/R3
= 1/6ohm + 1/6ohm
=2/6 ohm
Rp = 3 ohmR total = ((R1+R2)//R3) + R4
=
(Rs//R3) + R4
=
Rp + R4
= 3ohm + 7ohm
= 10 ohm
4. Sound as a wave
The
waves are
part of the energy vibrations that
propagate. Sound waves can not
propagate in a vacuum because there is no in
the room air particles in the air.
Wave by the medium can be divided into 2 types:Mechanical waves in the wave propagation need a
medium. Examples of mechanical
waves are sound waves.
- Electromagnetic waves are waves that do not need the propagation medium. Examples of electromagnetic waves are light wave
- Electromagnetic waves are waves that do not need the propagation medium. Examples of electromagnetic waves are light wave
Wave direction to knock divided into 2 types:
- Transverse waves are waves that knock the direction perpendicular to the direction of vibration. For example, light waves.
- Longitudinal waves are waves that knock the direction parallel to the direction of vibration. Longitudinal wave consists of density and strain
The waves can be used in everyday life such as artificial satellites, solar cells, sonar, and oil and gas exploration.
- Transverse waves are waves that knock the direction perpendicular to the direction of vibration. For example, light waves.
- Longitudinal waves are waves that knock the direction parallel to the direction of vibration. Longitudinal wave consists of density and strain
The waves can be used in everyday life such as artificial satellites, solar cells, sonar, and oil and gas exploration.
sound is a mechanical wave that is longitudinal. According frequency sound
waves are divided into 3 infrasonic, and ultrasonic audiosonic. The third sound
is the result of the vibration of an object. Vibration sound sources surrounding
air vibrate and propagate all directions as a longitudinal wave. Sound waves are
collected by the outer ear and the eardrum vibrate further.
Wave type sound is just sound audio that can be captured by the human ear. Sound waves propagate in the form of density and strain so that the sound can travel through solids, liquids, and gases. Sound waves are very easy to experience diffraction. That is why we can hear the sound of a car engine before the bend in the road even though we have not seen the car because it was blocked by tall buildings alongside a bend.
Wave type sound is just sound audio that can be captured by the human ear. Sound waves propagate in the form of density and strain so that the sound can travel through solids, liquids, and gases. Sound waves are very easy to experience diffraction. That is why we can hear the sound of a car engine before the bend in the road even though we have not seen the car because it was blocked by tall buildings alongside a bend.
