<< Chapter < Page Chapter >> Page >

Conceptual questions

What is the relationship between the accuracy and uncertainty of a measurement?

Got questions? Get instant answers now!

Prescriptions for vision correction are given in units called diopters (D). Determine the meaning of that unit. Obtain information (perhaps by calling an optometrist or performing an internet search) on the minimum uncertainty with which corrections in diopters are determined and the accuracy with which corrective lenses can be produced. Discuss the sources of uncertainties in both the prescription and accuracy in the manufacture of lenses.

Got questions? Get instant answers now!

Problems&Exercises

Express your answers to problems in this section to the correct number of significant figures and proper units.

Suppose that your bathroom scale reads your mass as 65 kg with a 3% uncertainty. What is the uncertainty in your mass (in kilograms)?

2 kg

Got questions? Get instant answers now!

A good-quality measuring tape can be off by 0.50 cm over a distance of 20 m. What is its percent uncertainty?

Got questions? Get instant answers now!

(a) A car speedometer has a 5.0 % size 12{5.0%} {} uncertainty. What is the range of possible speeds when it reads 90 km/h size 12{"90"" km/h"} {} ? (b) Convert this range to miles per hour. 1 km = 0.6214 mi size 12{"1 km" "=" "0.6214 mi"} {}

  1. 85 . 5 to 94 . 5 km/h size 12{"85" "." 5" to 94" "." "5 km/h"} {}
  2. 53 . 1 to 58 . 7 mi/h size 12{"53" "." 1" to 58" "." "7 mi/h"} {}
Got questions? Get instant answers now!

An infant’s pulse rate is measured to be 130 ± 5 size 12{"130" +- 5} {} beats/min. What is the percent uncertainty in this measurement?

Got questions? Get instant answers now!

(a) Suppose that a person has an average heart rate of 72.0 beats/min. How many beats does he or she have in 2.0 y? (b) In 2.00 y? (c) In 2.000 y?

(a) 7 . 6 × 10 7  beats size 12{7 "." 6 times "10" rSup { size 8{7} } " beats"} {}

(b) 7 . 57 × 10 7  beats size 12{7 "." "57" times "10" rSup { size 8{7} } " beats"} {}

(c) 7 . 57 × 10 7  beats size 12{7 "." "57" times "10" rSup { size 8{7} } " beats"} {}

Got questions? Get instant answers now!

A can contains 375 mL of soda. How much is left after 308 mL is removed?

Got questions? Get instant answers now!

State how many significant figures are proper in the results of the following calculations: (a) 106 . 7 98 . 2 / 46 . 210 1 . 01 size 12{ left ("106" "." 7 right ) left ("98" "." 2 right )/ left ("46" "." "210" right ) left (1 "." "01" right )} {} (b) 18 . 7 2 size 12{ left ("18" "." 7 right ) rSup { size 8{2} } } {} (c) 1 . 60 × 10 19 3712 size 12{ left (1 "." "60" times "10" rSup { size 8{ - "19"} } right ) left ("3712" right )} {} .

  1. 3
  2. 3
  3. 3
Got questions? Get instant answers now!

(a) How many significant figures are in the numbers 99 and 100? (b) If the uncertainty in each number is 1, what is the percent uncertainty in each? (c) Which is a more meaningful way to express the accuracy of these two numbers, significant figures or percent uncertainties?

Got questions? Get instant answers now!

(a) If your speedometer has an uncertainty of 2 . 0 km/h size 12{2 "." 0" km/h"} {} at a speed of 90 km/h size 12{"90"" km/h"} {} , what is the percent uncertainty? (b) If it has the same percent uncertainty when it reads 60 km/h size 12{"60"" km/h"} {} , what is the range of speeds you could be going?

a) 2 . 2 % size 12{3 "." 3%} {}

(b) 59 to 61 km/h size 12{"59 to 61 km/h"} {}

Got questions? Get instant answers now!

(a) A person’s blood pressure is measured to be 120 ± 2 mm Hg size 12{"120" +- 2" mm Hg"} {} . What is its percent uncertainty? (b) Assuming the same percent uncertainty, what is the uncertainty in a blood pressure measurement of 80 mm Hg size 12{"80"" mm Hg"} {} ?

Got questions? Get instant answers now!

A person measures his or her heart rate by counting the number of beats in 30 s size 12{"30"" s"} {} . If 40 ± 1 size 12{"40" +- 1} {} beats are counted in 30 . 0 ± 0 . 5 s size 12{"30" "." 0 +- 0 "." 5" s"} {} , what is the heart rate and its uncertainty in beats per minute?

80 ± 3 beats/min size 12{"80" +- 3`"beats/min"} {}

Got questions? Get instant answers now!

What is the area of a circle 3 . 102 cm size 12{3 "." "102"" cm"} {} in diameter?

Got questions? Get instant answers now!

If a marathon runner averages 9.5 mi/h, how long does it take him or her to run a 26.22-mi marathon?

2 . 8 h size 12{2 "." 8" h"} {}

Got questions? Get instant answers now!

A marathon runner completes a 42 . 188 -km size 12{"42" "." "188""-km"} {} course in 2 h size 12{2" h"} {} , 30 min, and 12 s size 12{"12"" s"} {} . There is an uncertainty of 25 m size 12{"25"" m"} {} in the distance traveled and an uncertainty of 1 s in the elapsed time. (a) Calculate the percent uncertainty in the distance. (b) Calculate the uncertainty in the elapsed time. (c) What is the average speed in meters per second? (d) What is the uncertainty in the average speed?

Got questions? Get instant answers now!

The sides of a small rectangular box are measured to be 1 . 80 ± 0 . 01 cm size 12{1 "." "80" +- 0 "." "01"" cm"} {} , {} 2 . 05 ± 0 . 02 cm, and 3 . 1 ± 0 . 1 cm size 12{2 "." "05" +- 0 "." "02"" cm, and 3" "." 1 +- 0 "." "1 cm"} {} long. Calculate its volume and uncertainty in cubic centimeters.

11 ± 1 cm 3 size 12{"11" +- 1" cm" rSup { size 8{3} } } {}

Got questions? Get instant answers now!

When non-metric units were used in the United Kingdom, a unit of mass called the pound-mass (lbm) was employed, where 1 lbm = 0 . 4539 kg size 12{1" lbm"=0 "." "4539"`"kg"} {} . (a) If there is an uncertainty of 0 . 0001 kg size 12{0 "." "0001"`"kg"} {} in the pound-mass unit, what is its percent uncertainty? (b) Based on that percent uncertainty, what mass in pound-mass has an uncertainty of 1 kg when converted to kilograms?

Got questions? Get instant answers now!

The length and width of a rectangular room are measured to be 3 . 955 ± 0 . 005 m size 12{3 "." "955" +- 0 "." "005"" m"} {} and 3 . 050 ± 0 . 005 m size 12{3 "." "050" +- 0 "." "005"" m"} {} . Calculate the area of the room and its uncertainty in square meters.

12 . 06 ± 0 . 04 m 2 size 12{"12" "." "06" +- 0 "." "04"" m" rSup { size 8{2} } } {}

Got questions? Get instant answers now!

A car engine moves a piston with a circular cross section of 7 . 500 ± 0 . 002 cm size 12{7 "." "500" +- 0 "." "002"`"cm"} {} diameter a distance of 3 . 250 ± 0 . 001 cm size 12{3 "." "250" +- 0 "." "001"`"cm"} {} to compress the gas in the cylinder. (a) By what amount is the gas decreased in volume in cubic centimeters? (b) Find the uncertainty in this volume.

Got questions? Get instant answers now!

Questions & Answers

what is distribution of trade
Grace Reply
what's acceleration
Joshua Reply
The change in position of an object with respect to time
Mfizi
how i don understand
Willam Reply
how do I access the Multiple Choice Questions? the button never works and the essay one doesn't either
Savannah Reply
How do you determine the magnitude of force
Peace Reply
mass × acceleration OR Work done ÷ distance
Seema
Which eye defect is corrected by a lens having different curvatures in two perpendicular directions?
Valentina Reply
acute astigmatism?
the difference between virtual work and virtual displacement
Noman Reply
How do you calculate uncertainties
Ancilla Reply
What is Elasticity
Salim Reply
using a micro-screw gauge,the thickness of a piece of a A4 white paper is measured to be 0.5+or-0.05 mm. If the length of the A4 paper is 26+or-0.2 cm, determine the volume of the A4 paper in: a). Cubic centimeters b). Cubic meters
Ancilla Reply
what is module
Alex Reply
why it is possible for an object(man) to stay on air without falling down?
akande Reply
its impossible, what do you mean exactly?
Ryan
Exactly
Emmanuella
it's impossible
Your
Why is it not possible to stand in air?
bikko
the air molecules are very light enough to oppose the gravitational pull of the earth on the man..... hence, freefall occurs
Arzail
what is physics
Joshua Reply
no life without physics ....that should tell you something
Exactly
Emmanuella
😎👍
E=MC^2
study of matter and energy and an inter-relation between them.
Minahil
that's how the mass and energy are related in stationery frame
Arzail
Ketucky tepung 10m
firdaus
Treeskin, 6m Cloud gam water 2m Cloud gam white 2m And buur
firdaus
Like dont have but have
firdaus
Two in one
firdaus
Okay
firdaus
DNA card
firdaus
hey am new over hear
Shiwani
War right? My impesilyty again. Don't have INSURAN for me
firdaus
PUSH
firdaus
I give
firdaus
0kay
firdaus
Hear from long
firdaus
Hehehe
firdaus
All physics... Hahahaha
firdaus
Tree skin and two cloud have tokside maybe
firdaus
Sold thing
firdaus
PUSH FIRST. HAHAHAAHA
firdaus
thanks
firdaus
Kinetic energy is the energy due to montion of waves,electrons,atoms, molecule,substances an object s.
Emmanuella
Opjective 0
firdaus
Atom nber 0
firdaus
SOME N
firdaus
10.000m permonth. U use momentom with me
firdaus
hi
Hilal
plz anyone can tell what is meteor and why meteor fall in night? can meteor fall in the day
Hilal
meteor are the glowy (i.e. heated when the enter into our atmosphere) parts of meteoroids. now, meteoroids are the debris resulting from the collision of asteroids or comets. yes, it occurs in daytime too, but due to the daylight, we cant observe it as clearly as in night
Arzail
thank's
Hilal
hello guys
Waka
wich method we use to find the potential on a grounded sphere
Noman
with out a physics the life is nothing to see
Yilma Reply
What do you want to talk about😋😋
Emmanuella
the study of all the natural events occuring around us..... this is Physics (until those events obey the laws of physics)
Arzail
Conservation of energy😰
Emmanuella
yeah, that too
Arzail
Energy, it always remains there in a physical system. it can only take the form either in motion (kinetic energy) or in rest (potential energy)
Arzail
In nature organisms feed on one another in an orderly way.
Emmanuella
that describes the food chain, in which we humans are at the top
Arzail
The energy that came initially from the sun 🌞is converted into a form in which it can be stored in green plant.
Emmanuella
Therefore, there is conservation of energy.
Emmanuella
DNA CARD
firdaus
"card"
firdaus
Darag
firdaus
What is x-ray
Daniel Reply
x-rays are electromagnetic Ray's produced when electrons with very high acceleration is brought to a stop by a target metal..
Felix
DNA CARD. DNA BLOOD(DARAH)
firdaus
@firdaus What is this DNA card? can I get to know?
Arzail
Practice Key Terms 6

Get the best College physics course in your pocket!





Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics' conversation and receive update notifications?

Ask