NIM : RSA1C311015
Subject : English for Special Purpose
TASK 1
1. I believe all of you have seen Ferris Wheel. Ferris Wheel is moves in circle. when the is Ferris Wheel at maximum height, then EK is 0.and while the Ferris Wheel its lowest point, then EK is maximum.
Every moving object has energy. The energy possessed by a moving object is called kinetic energy. In short, kinetic energy is energy that is resulted when an object moves.
There are two kinds of energy kinetic, they are:
* Translation kinetic
Translational kinetic energy is the energy possessed by a moving object on a straight track
* Rotation kinetic.
While the translational kinetic energy is the energy possessed by objects moving in a straight line, the rotational kinetic energy is the energy possessed by objects that perform the rotary motion
every moving body must have kinetic energy. kinetic energy possessed by the rotating object is called kinetic energy of rotation, the amount of kinetic energy can be derived from the following translation:
KE = 1/2 mv^2
the rotational kinetic energy formula KE = 1/2 I〖ω 〗^2
problems:
a Ferris Wheel have diameter 3 m with a moment of inertia of 120 kg m^2 rotates with a speed of 0.5 rps. What is the kinetic energy?
Solution:
Known: I= 120 kg m^2
ω = 0,5 rps= 0,5 (2π) rad/s= π rad/s
answer :
EK= 1/2 I〖ω 〗^2
= 1/2 120 kg m^2 . π rad/s
= 60 π Joule
so the conclusion is 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 v for translation kinetic energy. In rotation kinetic energy that belongs of moment of inertia I and speed of ω
TASK 2
2.The pendulum is an object tied to a string and can swing freely and periodic basis the work of an ancient wall clock that has a swing.
The period of a pendulum swing is determined by the length of the pendulum, the force of gravity and amplitude. The period does not depend on the mass of the pendulum. If the amplitude of the swing is limited by the small, simple pendulum period T, the time required for one cycle
in this Experiment. fricttion force of air is ignored
Purpose: measuring the gravity
Tools and materials :
In these experiments, the equipment and materials used are as following.
1. Ruler
2. Protractor
3. Stopwatch
4. Load
5. Hook
6. Thread
7. Pedestal table
Procedure:
1. Measure the length of rope L
2. Give the maximum deviation 50
3. Measure the time required for the pendulum to reach 10 periods
4. Repeat the above steps for 10 different lengths of the thread.
TASK 3
3. Electrical current is defined as charges which flows from the highest potential positive chargest tnto the lowest. electrical current is propertional to the amount of charge that flows in a conductor and inversly to the time.
PROBLEM:
within 2 minutes a charge of 60 C flows through a conductor , whhat is the current that flows during those 2 minutes?
SOLUTION:
as we know, the formula is the electrical current is proportional with the charge and inversly with time.
SO : I=q/t
I= 60/120
if there is the situation where charge is 60 colomb and the time current takes to flow through the conductor is 120 second. the electrical current is resulted by dividing the charge with the time. the answer to the roblem above is,0,5 ampere
TASK 4
4. The sound is a form of wave propagation phenomenon density and strain-. Thus, the sound is a longitudinal wave. In propagation, sound needs a medium. Medium for propagation in the form of gas, liquid, or solid. There are 3 possible causes sound:
1. Reflecting sound waves
Why in the concert hall posted silencer?
To avoid resonance, then in theaters or concert hall walls are lined by a substance or substances silencer soundproof. Substance soundproof used are wool, cotton, or cardboard. In a concert hall music, silencer shaped plates hanging on the ceiling to eliminate resonance.
2. Refraction of sound waves.
Why at night the sound of thunder louder than the day?
During the day, the air in the upper layers colder than the lower layer. the propagation of sound in cold temperatures is smaller than the heat. So, during the day, the sound of thunder travels from upper layer of the atmosphere leading to lower air layer will be refracted away from the normal line. at night, the air in the lower layer of the air cooler the upper layer. so that, the speed of sound on the bottom layer is smaller than in the upper layer. refraction sound of thunder approaching normal lines at night is what causes thunder sounded louder .
3. Diffraction of sound waves.
Sound waves are very susceptible to diffraction. That is why we can hear the sound of a car engine before the street corner even though we have not seen the car because it obstructed by a tall building on the edge of the corner.
Why sound waves having diffraction?
Sound waves in the air has a wavelength in the range of a few centimeters to several meters. That is the reason why the sound waves very easily difraction
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