0.11 Phy1080: motion -- variable velocity and acceleration  (Page 3/19)

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According to this author , there is no universally accepted name for the rate of change of jerk.

The algebraic sign of acceleration

When the velocity of a moving object increases, that is viewed as positive acceleration. When the velocity of the object decreases, that is viewed asnegative acceleration.

Uniform or variable acceleration

Acceleration may be uniform or variable. It is uniform only if equal changes in velocity occur in equal intervals of time.

A vector quantity

Acceleration has both direction and magnitude. Therefore, acceleration is a vector quantity.

The units for acceleration

The above definition for acceleration leads to some interesting units for acceleration. For example, consider a situation in whichthe velocity of an object changes by 5 feet/second in a one-second time interval. Writing this as an algebraic expression gives us

(5 feet/second)/second

Multiplying the numerator and the denominator of the fraction by 1/second gives us

5 feet/(second*second)

This is often written as

5 feet/second^2

which is pronounced five feet per second squared.

The acceleration of gravity

The exercises in the remainder of this module are based on the following two assumptions:

• For practical purposes, the effect of the acceleration of gravity is the same regardless of the height of an object above the surface of the earth,provided that the distance above the surface of the earth is small relative to the radius of the earth.
• In the absence of an atmosphere, all objects fall toward the earth with the same acceleration regardless of their masses.

Let's examine the validity of these two assumptions.

Newton's law of universal gravitation

This law states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. (Separately ithas been shown that large spherically symmetrical masses attract and are attracted as if all their mass were concentrated at their centers.)

Effect of gravity versus altitude

An object at the surface of the earth is approximately 3963 miles from the center of the earth. An object that is six miles above the surface of the earth(typical flying altitude for a passenger plane) is approximately 3969 miles from the center of the earth.

Therefore, (if I didn't make an arithmetic error) the gravitational attraction between the earth and that object changes by less than 0.5 percentwhen the object is transported from the surface of the earth to a position that is six miles above the surface of the earth.

For practical purposes, therefore, we can assume that the acceleration of gravity is constant up to at least 32000 feet above the surface of the earth.

Acceleration is independent of mass

Newton's law, as applied to the gravitational attraction of the earth, expressed in algebraic terms, looks something like the following :

f =E*m/d^2

where

• f is the attractive force between the earth and another object
• E is the mass of the earth
• m is the mass of the other object
• d is the distance between the center of mass of the earth and the center of mass of the other object

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
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
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