these are practice questions that i have the answer to, but i don't know how to solve them:
1.A human hair is approximately 50um in diameter. Express this diameter in meters.
2. if a radio has a period of 1us, what is the wave's period in sesconds?
3. A hydrogen atom has a diameter of about 10nm.
a. Express this diameter in meters
b. Express this dia....in millimeters
c. Express......dia....in micrometers
P.S. BTW you WILL want to learn how to do these conversions because when you have a test, the site will not available to you!
Sra
sorry, i meant to write seconds.
thanks alot
1. μ represents Greek "mu" or 10^-6 or micro
so 50 *10^-6
or 5.0*10^-5 meters
2. same deal 1 μ second is 10^-6 second
3. n, nano, means 10^-9 so 10 nm = 10^-9 = 1.0 * 10^-8 m
10^-8 m/10^-3 m/mm = 10^-5 mm
10^-8 m / 10^-6 m/μm = 10^-2 μm
on that site, i am looking under lenghts, metric convertor, but i don't see diameter
Diameter is a measure of length.
thanks Damon i understand it now:
so if the question is : the distance between the sun and Earth is about 1.5*10^11m. Express this distance with an SI prefix and in kilometers.
im getting . 1.5*10^8 km?
Yes 1.5*10^8 km is fine for
1.5*10^11 m . Note that there is a space between the number and the unit, as shown in Damon's post, and when you come onto it there is a space between units as well.
.
It is good practice to get into the habit of leaving spaces now as you write/type.
I do want to mention the very old FORTRAN symbology for powers of ten. FORTRAN did it because there were no superscripts in its ASCII, as is here. SO personally, I like writing here
for 3.3 *104 to use 3.3E4
how do you figure out if a value is accurate or precise?
three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. the known mass is 10.68 g.
i don't understand if the values are precise or accurate or how to even figure that out!!
Precise indicates how many significant digits there are in the measurement. Those values are precise to three digits, to the hundretths. That does not mean they are accurate, and in this case there is signifcant error from the known. Accuracy is measured by either percent error, or absolute error.
Pretend you know it is noon, and your see your watch indicates 10:43:54. That is pretty precise, but not accurate.