



Section summary
 Time is measured in terms of change, and its SI unit is the second (s). Elapsed time for an event is
$\mathrm{\Delta}t={t}_{\mathrm{f}}{t}_{0},$
where
${t}_{\mathrm{f}}$ is the final time and
${t}_{0}$ is the initial time. The initial time is often taken to be zero, as if measured with a stopwatch; the elapsed time is then just
$t$ .
 Average velocity
$\stackrel{}{v}$ is defined as displacement divided by the travel time. In symbols, average velocity is
$\stackrel{}{v}=\frac{\mathrm{\Delta}x}{\mathrm{\Delta}t}=\frac{{x}_{\text{f}}{x}_{0}}{{t}_{\text{f}}{t}_{0}}\text{.}$
 The SI unit for velocity is m/s.
 Velocity is a vector and thus has a direction.
 Instantaneous velocity
$v$ is the velocity at a specific instant or the average velocity for an infinitesimal interval.
 Instantaneous speed is the magnitude of the instantaneous velocity.
 Instantaneous speed is a scalar quantity, as it has no direction specified.
 Average speed is the total distance traveled divided by the elapsed time. (Average speed is
not the magnitude of the average velocity.) Speed is a scalar quantity; it has no direction associated with it.
Conceptual questions
There is a distinction between average speed and the magnitude of average velocity. Give an example that illustrates the difference between these two quantities.
Got questions? Get instant answers now!
If you divide the total distance traveled on a car trip (as determined by the odometer) by the time for the trip, are you calculating the average speed or the magnitude of the average velocity? Under what circumstances are these two quantities the same?
Got questions? Get instant answers now!
Problems&Exercises
(a) Calculate Earth's average speed relative to the Sun. (b) What is its average velocity over a period of one year?
(a)
$3\text{.}\text{0}\times {\text{10}}^{4}\phantom{\rule{0.25em}{0ex}}\text{m/s}$
(b) 0 m/s
Got questions? Get instant answers now!
A helicopter blade spins at exactly 100 revolutions per minute. Its tip is 5.00 m from the center of rotation. (a) Calculate the average speed of the blade tip in the helicopter's frame of reference. (b) What is its average velocity over one revolution?
Got questions? Get instant answers now!
The North American and European continents are moving apart at a rate of about 3 cm/y. At this rate how long will it take them to drift 500 km farther apart than they are at present?
$2\times {\text{10}}^{7}\phantom{\rule{0.25em}{0ex}}\text{years}$
Got questions? Get instant answers now!
Land west of the San Andreas fault in southern California is moving at an average velocity of about 6 cm/y northwest relative to land east of the fault. Los Angeles is west of the fault and may thus someday be at the same latitude as San Francisco, which is east of the fault. How far in the future will this occur if the displacement to be made is 590 km northwest, assuming the motion remains constant?
Got questions? Get instant answers now!
On May 26, 1934, a streamlined, stainless steel diesel train called the Zephyr set the world's nonstop longdistance speed record for trains. Its run from Denver to Chicago took 13 hours, 4 minutes, 58 seconds, and was witnessed by more than a million people along the route. The total distance traveled was 1633.8 km. What was its average speed in km/h and m/s?
$\text{34}\text{.}\text{689 m/s}=\text{124}\text{.}\text{88 km/h}$
Got questions? Get instant answers now!
Questions & Answers
If a prism is fully imersed in water then the ray of light will normally dispersed or their is any difference?
the same behavior thru the prism out or in water bud abbot
Ju
If this will experimented with a hollow(vaccum) prism in water then what will be result ?
Anurag
What was the previous far point of a patient who had laser correction that reduced the power of her eye by 7.00 D, producing a normal distant vision power of 50.0 D for her?
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the power of her eyes. What is the closest object she can see clearly?
Jaydie
In what ways does physics affect the society both positively or negatively
how can I read physics...am finding it difficult to understand...pls help
try to read several books on phy don't just rely one. some authors explain better than other.
Ju
And don't forget to check out YouTube videos on the subject. Videos offer a different visual way to learn easier.
Ju
I have a exam on 12 february
the speed of something in a given direction.
Ju
what is a magnitude in physics
Propose a force standard different from the example of a stretched spring discussed in the text. Your standard must be capable of producing the same force repeatedly.
What is meant by dielectric charge?
what happens to the size of charge if the dielectric is changed?
omega= omega not +alpha t
derivation
u have to derivate it respected to time ...and as w is the angular velocity uu will relace it with "thita × time""
Abrar
do to be peaceful with any body
the angle subtended at the center of sphere of radius r in steradian is equal to 4 pi how?
if for diatonic gas Cv =5R/2 then gamma is equal to 7/5 how?
Saeed
displacement in easy way.
binding energy per nucleon
Source:
OpenStax, College physics for ap® courses. OpenStax CNX. Nov 04, 2016 Download for free at https://legacy.cnx.org/content/col11844/1.14
Google Play and the Google Play logo are trademarks of Google Inc.