# 0.19 Phy1170: energy -- work  (Page 2/7)

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Conditions for constant velocity

We know that the statement means at least the following things:

• At some point in the past, there was an unbalanced force applied to the object to cause it to begin moving to the right. That force is ignored bythe statement of the problem.
• At the beginning of the time frame covered by the problem, the object was in equilibrium, moving at a constant velocity to the right.
• During the time frame of the problem, there must be a 1 newton balancing force being exerted to the left to prevent the 1 newtonforce being applied to the right from causing the object to accelerate towards the right. That force is also ignored by the statement of theproblem.

## Use your graph board for sketches

As a sighted person, I often find it useful to make sketches of the physical scenarios for problems of the types that I will discuss in this module.

You may also find it useful to use your graph board to create "sketches" of the physical scenarios in order to better understand the solutions to theproblems.

## Work in everyday life

You hear the word work in many situations in everyday life. For example, someone might say "My gasoline bill is high because I have to drive a long wayto work every day."

Someone else might say "She works very hard at being popular."

Or, you might hear someone say "It's going to take a lot of work to lift that heavy sofa into the back of that truck."

The latter expression comes closest to describing what is mean by work in physics.

## Work in physics

According to College Physics by Mendenhall et al

If a body on which a force F is acting is displaced by a distance d, then the work done by the force is F*d*cos(theta), where theta is the angle betweenthe path d and the line of action of F.

Thus, the term work has a very precise meaning in physics. In equation form, we can represent work as

W = F * d * cos(theta)

where

• W represents work
• F represents a force that causes the displacement of an object
• d represents the magnitude of the displacement
• theta is the angle between the line of action of the force and the direction of the displacement

Three key ingredients

According to the Physics Classroom (see (External Link) ), there are three key ingredients to work: force , displacement , and cause .

In order for a force to qualify as having done work on an object, there must be a displacement and the force must cause the displacement.

Commonplace examples of work

Examples of work are commonplace in everyday life:

• A bulldozer pushing dirt. The bulldozer exerts a horizontal force to move the dirt.
• An elevator lifting people from the first to the tenth floor. The cable on the elevator exerts an upward force to move the people upward byapproximately 110 feet.
• You lifting your backpack full of books onto your back. Your muscles exert a force to raise several heavy books, possibly displacing them bothvertically and horizontally at the same time.

However, some things that we might initially think of as work don't really qualify as work according to the physics definition of work.

how do they get the third part x = (32)5/4
can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
a perfect square v²+2v+_
kkk nice
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
rolling four fair dice and getting an even number an all four dice
Kristine 2*2*2=8
Differences Between Laspeyres and Paasche Indices
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
is it 3×y ?
J, combine like terms 7x-4y
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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