A car is traveling at 118 km/h. What is its speed in mm/h?

Question

aaronq · Answer

convert km to mm

1 km = 1 000 000 mm

anonymous · Answer

Is there a way u could show me in the dimensional analysis?

aaronq · Answer

$118 \;km*\dfrac{1,000,000 mm}{1\;km}$


then just add "per hour", \h, to the answer

anonymous · Answer

So its 118000000 right?

aaronq · Answer

don't forget the units

anonymous · Answer

Yea ok

anonymous · Answer

Is that it?

aaronq · Answer

you tell me, do you think that answers the question?

anonymous · Answer

Yes but wat abt mm/h?

aaronq · Answer

what about it?

anonymous · Answer

Can u please show me how to do it step by step in dimensional analysis while explaning?

aaronq · Answer

we already did it. We found how many mm are in said km, since the time units are the same, there is nothing else to be done.

anonymous · Answer

Oooh lol sorry. I was thinking of the example the teacher showed me today. Sorry

aaronq · Answer

it's okay. if you were also changing the time intervals (say hours to seconds) then you would have do further conversions.

anonymous · Answer

Can u show me an example?

anonymous · Answer

Please

aaronq · Answer

1 km/h to 1 m/sec

$1\; km/hr*\dfrac{1000\;\color{red}{m}}{1\;km}*\dfrac{1\;hr}{60\;min}*\dfrac{1\;min}{60\;\color{red}{sec}}$

notice the units are cancelling out, and you only end up with m/sec

aaronq · Answer

you're essentially cancelling out units by multiplying by its values.

60 min in 1 hr

1000 m in 1 km

etc.

anonymous · Answer

Ooh k that makes sense. Got it thanx!! Btw do u kno an app for this?

aaronq · Answer

ok cool. no, i'm sure if you search there'll be one though.

anonymous · Answer

Alright...im moving to algebra 2 can u help me please?

aaronq · Answer

I gotta go in a few min, sorry. You should ask those questions in the math section, though.

anonymous · Answer

K thanxx!!!