# 0.11 Phy1080: motion -- variable velocity and acceleration  (Page 7/19)

 Page 7 / 19

Estimating variable velocity graphically

Assuming that you are able to create a plot of displacement versus time at closely-spaced points, you can estimate the variable velocity curve byconnecting each pair of points with a straight line and measuring the slope of each such straight line segment. An estimate of the velocity during the intervaldefined by a pair of points is the slope of the line that connects those points. The closer the points are, the better will be the estimate of thevelocity at a point half way between those two points.

In the situation where you are able to collect enough data to draw a smooth curve of displacement versus time, the instantaneous velocity at any point onthat curve is the slope of a line that is tangent to the curve at that point. Note, however, that the construction of such a tangent line is no small feat.

Units of velocity

If you recall your high school geometry course, you may remember that the slope of a line is given by the "rise over run." In other words, the slope ofthe line is the ratio of the height to the base of a right triangle for which the hypotenuse is on or parallel to the line.

Estimate some variable velocity values

At this point, I encourage you to use a straight edge, place it firmly against two pins that define a time interval on your graph board,estimate the slope of the edge, and record that slope as your estimate of the velocity at the center of that time interval.

Explanation of the code

The code in Listing 1 begins by declaring and initializing values to contain the parameters of the problem:

• The acceleration of gravity in feet/sec^2. Note that this value is negative indicating that the gravitational attraction is toward the centerof the earth (down).
• The initial velocity of the arrow in feet/sec. This value is positive because the direction of velocity is away from the center of the earth (up).
• The height of the arrow when it is released, positive values meaning up from the ground.
• The time interval at which successive estimates of the height of the arrow will be computed.

Working variables

Following that, the code in Listing 1 declares and initializes two working variables for time and distance that will change as the program progresses.

Then Listing 1 declares and initializes a variable named sp that is used solely to insert spaces between the columns in the output display.

A while loop

A while loop is used to evaluate the equation given earlier , to compute and display the height of the arrow every 0.25 seconds for as long as the arrow is above theground (height is positive). The loop continues to iterate and display time and height values in two separate columns (see Figure 4 ) until the computation produces one negative height value.

When the test at the top of the while loop determines that the previously-computed value for height was negative,

• The body of the loop is skipped.
• The "End Script" message is displayed.
• The script terminates.

As you can see, this is not a complicated script in comparison with some of the scripts that were presented in earlier modules.

#### Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
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
Google
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
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
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
Brian Reply
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?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
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 ?
Bob Reply
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?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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