# 0.2 Tg physical science - chapter contexts  (Page 7/10)

 Page 7 / 10

Refer to the chapter on units. By showing that the units $\mathrm{kg}·m·{s}^{-2}$ are equal to J, and mixing units and energy calculations will assist learners to be more watchful when solving problems to convert given data to SI base quantities and units.

Kinetic energy is the energy an object has because of its motion. The kinetic energy of an object can be determined by using the equation:

${E}_{k}=\frac{1}{2}{\mathrm{mv}}^{2}$

In words, mechanical energy is defined as the sum of the gravitational potential energy and the kinetic energy, and as an equation:

${E}_{M}={E}_{P}+{E}_{K}=\mathrm{mgh}+\frac{1}{2}{\mathrm{mv}}^{2}$

Both the laws of conservation of energy and conservation of mechanical energy are states. To solve problems the latter is applied in the form:

$\begin{array}{}{U}_{\mathrm{top}}={U}_{\mathrm{bottom}}\\ {E}_{P\mathrm{top}}+{E}_{K\mathrm{top}}={E}_{P\mathrm{bottom}}+{E}_{K\mathrm{bottom}}\end{array}$

To assess their degree of understanding of the content and concepts, learners are advised to engage in studying the worked examples and do the set problems.

## Transverse pulses

Transverse pulses on a string or spring are discussed, but first the questions are asked: What is a medium? What is a pulse? The following terms related to transverse pulse are introduced, defined and explained: position of rest, pulse length, amplitude and pulse speed. When a transverse pulse moves through the medium, the particles in the medium only move up and down. This important concept is illustrated by a position vs. time graph. When learners engage in doing the investigation, drawing a velocity-time graph and studying the worked example, they will get to grips with the concepts. When two or more pulses pass through the same medium at the same time, it results in constructive or destructive interference. This phenomenon is explained by superposition, the addition of amplitudes of pulses.

## Transverse waves

A transverse wave is a wave where the movement of the particles of the medium is perpendicular to the direction of propagation of the wave. Concepts addressed include: wavelength, amplitude, frequency, period, crests, troughs, points in phase and points out of phase, the relationship between frequency and period, i.e. $f=\frac{1}{T}$ and $T=\frac{1}{f}$ , the speed equation, $v=f\lambda$ .

## Longitudinal waves

In a longitudinal wave, the particles in the medium move parallel to the direction in which the wave moves. It is explained how to generate a longitudinal wave in a spring. While transverse waves have peaks and troughs, longitudinal waves have compressions and rarefactions. A compression and a rarefaction is defined, explained and illustrated. Similar to the case of transverse waves, the concepts wavelength, frequency, amplitude, period and wave speed are developed for longitudinal waves. Graphs of particle position, displacement, velocity and acceleration as a function of time are presented. Problems set on the equation of wave speed for longitudinal waves, $v=f\lambda$ , concludes this section.

## Sound waves

Sound is a longitudinal wave. The basic properties of sound are: pitch, loudness and tone. Illustrations are used to explain the difference between a low and a high pitch and a soft and a loud sound. The speed of sound depends on the medium the sound is travelling in. Sound travels faster in solids than in liquids, and faster in liquids than in gases. The speed of sound in air, at sea level, at a temperature of formula ${21}^{°}C$ and under normal atmospheric conditions, is $344m·{s}^{-1}$ . Frequencies from 20 to 20 000 Hz is audible to the human ear. Any sound with a frequency below 20 Hz is known as an infrasound and any sound with a frequency above 20 000 Hz is known as an ultrasound.

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
hi
Loga
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
how did you get the value of 2000N.What calculations are needed to arrive at it
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Purification of water by natural plants and wetlands