Question

Use dimensional analysis to find the number of cm/min in 5.8 m/hr. Show your work and be sure to calculate the answer in the correct number of significant figures.

Answer 1

100 cm = 1 m
60 min = 1 hr
do the math

Answer 2

I don't know how to do dimensional analysis..

Answer 3

this is not dimensional analysis.

this is conversion of units

you know how many Metres/Hour
so start by working out how many CENTIMETERS/Hour

(hint: there are MORE cemtimeters because there are 100cm in 1 m)

THEN
Work out how many cm/MINUTE

(Hint: there are LESS per minute becausse 1 hour = 60 mins)

so there are 2 simple multiplication or division sums to do to get to the answer

Answer 4

Wait so why is the teacher telling me to do dimensional analysis if it's not dimensional analysis?? I'm aware of how to convert units. I was confused about the other part, I guess I can see why. lol

Answer 5

I don't know why you have been told this.

'Dimensional Analysis' involves the 'dimensions' of measurements, independently odf the UNITS

Typical DIMENSIONS are Length, Mass, Time
The UNITS of these can be Metres, Furlongs, Light Years / mg, lb, megaton / sec, millenium

You can convert between UNITS - but you cannot convert Dimensions

Answer 6

Thank you so much! I watched videos and people were using different units/dimensions, and just doing it completely different altogether. I'll email my teacher, maybe she made a mistake. :)

Answer 7

I have seen this expression used elsewhere for this type of calculation.

Maybe it is part of some US based course - but it is strictly being used incorrectly.

I did not tackle 'Dimensional Analysis' until well into a Degree in Engineering - it is commonly used inthe analysis of fluid flow for example.

Answer 8

this is dimensional analysis, just a fancy term for unit conversion in PHYSICS or a MATH course, not an engineering course.
sure it might be different there, but a word can have many meanings.

Answer 9

Ahhh, well I'll just ask her anyways and see how it goes. :) Thanks guys for your help!

Answer 10

let me clarify, i meant in a beginner math or physics course typically in the US (I do not know about engineering here), so yes it might be completely different from where you've studied it.

Answer 11

A google search reveals that the term IS used for this type of question - but to me it is simply a conversion of units . The other term simply confuses it - since the Dimensions do not change (both cm/sec AND m/hour have DIMENSION LENGTH/TIME)

Answer 12

http://www.chem.tamu.edu/class/fyp/mathrev/mr-da.html (for units)
https://en.wikipedia.org/wiki/Dimensional_analysis (for 'proper' DA)

Answer 13

i think we confused her with our terminology battle, lol.

Answer 14

nuff said :-)

Answer 15

Hahahaha, yeah I'm pretty confused omg