1.
Design a simple research about the kinetic energy
associated with your daily life and arrange your report in accord with the
sixth science process skills you have already understood!
Answer :
Have you been drive
a bicycle? What cause the bike moved?
Drive a bicycle
was an activity where moving the foot pedal and pedal bicycles moving the rear
wheels so the bike can move. foot adds kinetic energy to a process which the pedal
can rotate, then the rotation flowed kinetic energy into gear the rear wheels
so that the rear wheels spin and the bicycle move from point A to point B.
In everyday
life, we rarely find with a moving object along a straight path, for example bicycles
are not always moving forwards, sometimes turn if no curves, sometimes the
brakes if there are holes in the road. it's just a straight trajectory
model that we use to help us analyze the motion of objects, though more easily.
Remember that every moving
object must have velocity (v). Objects also have a mass (m). So kinetic energy is the energy
that actually describes the mass of an object moving at a certain speed. In mathematically, kinetic
energy of an object is expressed by the equation: K = ½ mv2
Kinetic energy
are grouped into two, namely the translational kinetic energy and rotational
kinetic energy. When cycling occurs rotational kinetic energy. Rotational kinetic energy is the
energy possessed by objects that perform rotational motion.
When I
experimented with using the bike, I can calculate kinetic energy by using the
formula. Given the mass of cyclists and mass 50kg 30kg bicycle with a speed of
2m/s, so it can be searched kinetic energy values :
K = 1/2 m v^2
K = 1/2(50kg+30kg)(2m/s)^2
K = 1/2(80kg)(4m^2/s^2)
K = 160 J
From the kinetic energy formula, we can
analyze that if the speed is increased then the energy will kineticnya
increases because kinetic energy is proportional to velocity.
We could take a conclusion that kind of
kinetic energy if we were cycling, rotation kinetic energy, because bicycles always
do rotational motion.
2.
Describe an experiment which associated with the
following terms : pendulum, frictional force and highest point. then enter the
terms into the procedure so that these terms included in your experiment!
Answer :
In this experiment, I
do experiment about simple pendulum
for know the value of gravitation. Simple pendulum consist of a
rope of length L and mass m pendulum ball.
The force who work on the ball pendulum is gravity (w
= mg) and rope tension force
FT. Weight force has
component mg cos
that directly with rope and mg sin
that perpendicular with rope. The
pendulum oscillates due to the
gravity component mg sin. In analyzing
the simple pendulum motion, the friction
force with the air can we ignorethe and mass of rope
is very negligible so we can
ignore relative to the ball. Because there is no air resistance force, the pendulum
did oscillation along
the arc with
the same amplitude. Pendulum hanging on the thread
that hanging vertically. The pendulum is pulled aside and released
so that things move back and
forth between two separate points,
lowest point and highest point.
The procedure :
1. Prepare the materials of experiment such as thread, 3 pendulum ball that have mass 50gr,80gr,100gr, hook, protractor, ruler, stopwatch.
2. Cut thread
more than 20cm, then bind thread on hook and be sure the length of thread is
20cm with measure the thread after binding.
3. Bind pendulum ball that have mass 50gr.
4. Pull aside and released
so that things move back and
forth between two separate points,
that are lowest point and highest point
so that make a deviation 10 with use
protactor.
5. Measure the time required for the pendulum to reach 10 period with stopwatch.
6. Repeat the above steps for 2 different length of thread (L) 25cm and 30cm, 2 different mass of pendulum ball that have mass 80gr and 100gr, and 2 different deviation 15 and 20.
7. Calculate the value of gravitation from 3 experiments with formula, g =4vhi/T^2 L
where, g = gravitation
T = period of pendulum
L = length of thread
the friction force ignore
8. Add up 3 value of gravitation and then divided by 3. We will find the value of gravitation.
L = length of thread
the friction force ignore
8. Add up 3 value of gravitation and then divided by 3. We will find the value of gravitation.
3.
Make a
simple calculation about electrical using the formula your well known. write
done your solution and explain it by using your sentence ( change the number or
symbol) !
Answer
:
A simple electrical circuit
consisting of a battery as a power source voltage ε and a load resistor R.
If
Vis 10 volts and R
is 2 Ω, specify electric current flowing !
Solution :
I = V/R
I = 10 volt/5ohm
I = V/R
I = 10 volt/5ohm
I = 5A
Read :
Read :
electric current (I) equal with voltage (V) and inversly with resistance
(R)
electric current (I) is ten volt divided by two ohm
electric current (I) is five ampere
4.
Make an essay about sound as a wave . then show at
least three evidences and exemplifying about it!
Answer :
Sound
is a mechanical wave that propagates because of the medium. Basically,
this group of sounds into the wave mechanics is based on the typical properties
by the wave groups. The sound has the
properties by wave mechanics. Sound
waves which include wave mechanics, has some properties / characteristics of
wave mechanics, such as:
1. Require a medium to propagate (water, air, solid). The
sound we find anywhere, as long as it's in there are air, water or solids.
2. Sound is a longitudinal wave. There
is a mechanical wave-shaped longitudinal, in example sound. But
there is a form of transverse waves on a string . The
sound is one of the waves, it’s longitudinal wave. Longitudinal
wave is a wave whose direction spread parallel or coincide with the direction
of vibration. Sound
waves can not propagate in a vacuum because there is no air particles in the
air in vacuum area. Sounds
is longitudinal waves because the area around the sound propagation is having
density and gap.
3. Sounds produced by vibrations generated by a musical
instrument, or other vibrating objects. Every object vibrates
definitely produce sound. But
not everything can be heard by our ears,it
depend on frequency, wave energy and the distance of the sound source
from us.
4. Sound is can’t do diffraction, polarization, refraction,
and other symptoms are experienced only transverse waves.
There are some
requirements that the sound can be heard by the human ear, such as:
• Sound have the
appropriate natural frequency same with limit of human hearing.
• Located at a distance that can be heard.
• Sound have enough
energy through human eardrum. At
the sound wave is a longitudinal wave, the sound propagates in a direction
parallel.
Three evidences :
-
human
voice
-
sound
of musical instrument
-
sound of a tuning forks.
Examples :
-
If
we are talking, we will feel vibration on our neck. It caused by vibration in the human
vocal cords, and propagates
through the medium of sound so that the air can be up to our ears.
-
If
we are playing guitar and we strum the guitar strings, so it will vibrating and
we will hear the sound of it.
- If we vibrate the tuning fork, so there is sound
from it. Tuning
fork tooth
movement in and out causing the surrounding air pressure difference. Low pressure areas around the sound
source that we are familiar
with gap, and
high-pressure area is that we know the density.
