Unit Conversion ad Significant Figures

[Soaring Crane]

Unit Conversion & Significant Figures

Greetings! I would just like to re-check my work:

1) What will be the mass in tons added to a car when its radiator is filled with antifreeze (d = 1.12 g/mL) if the radiator has a capacityof 3.99 gal?

Since density = mass/volume, mass = density*volume. So I change 3.99 gal into L and then mL. After I solve for mass, the answer is in grams, so I convert to tons (g -> kg -> ton). The number of sig. figs. is 3?

2) A running back in Europe lists his speed as 6.0 s for 31 m. How fast can he run 48 yds?

First, change 31 m -> yds. Now speed = distance/time. For time = distance/speed = [48 yds]/[(31m*1.0936 yd)/(6.0 s)]. Number of sig. figs. is 2?

3) A vehicle traveling at 57 mi per hr. has a fuel consumption of 18.6 mi per gal. If vechicle is carrying 5.3 gal of gasoline, how many min. does the driver have before vehicle runs out of fuel?

speed = 57 mi/hr; consumption = 18.6 mi/gal

18.6 mi/gal *5.3 gal = amt. of mi able to travel = distance, so time = distance/speed = (98.58 mi)/(57 mi/hr) = time in hr. -> convert to min ?

Number of sig. figs. is 2?

4) Diameter of C atom found in Pb of pencil is 0.15 nm. Suppose a line is drawn on piece of paper that has width of 0.330 mm, length of 52.000 mm, and thickness of 0.010 mm, determine number of atoms in that line.

First find Volume of line by l*w*h = mm^3, and covert to m^3 where 1 m^3 = (1000 mm)^3. Convert nm to m (0.15 nm*(1m/10^9 nm)). Now divide C atom's diameter by 2 for radius to use V = (4/3)*pi*r^3. Divide V of line/V of 1 C atom. Number of sig. figs. is 2?

Thank you.

 

[Astronuc]

Try this tutorial on significant digits.

http://ist-socrates.berkeley.edu/~chem1a/sigfigs/sigfig2.htm