Question

A man's average speed is 4.86 miles per hour. Express this in cm/sec .*dimensional analysis* .. the teacher answer is "217.32 cm/sec" however mine came out to be "217.26"
My work:
(4.86m/hr)(5280ft/1m)(12in/1ft)(2.54cm/1in)(1hr/3600sec) = 217.26cm/sec

Why are our answers different? The teacher provided answers to homework but students have to show work to get the answer.

Answer 1

A sphere of metal measures 4.6 cm in radius and has a density of 7.9 g/cm^3. What is the mass of a sphere? FYI: use V=4/3*pie sign*r^3 . . How would I set it up in dimensional analysis?

Answer 2

Accidently put my 2 question as answer to my first question sorry!! Hope someone still answers

Answer 3

I also get 217.261 cm/s
No idea what kind of rounding error produced 217.32

AAARFGBGGHH!! The Greek letter is <u><b>pi</b</u> not PIE!

4/3 π (4.6cm)^3 = 410 cm^3
Since mass = volume * density, that would be

410 cm^3 * 7.9 g/cm^3 = ...</b>

Answer 4

Thank you Steve! Sorry about the "pi" . . Thanks again!