How Do You Convert Units Using Given Conversion Factors?

[davie08]

Homework Statement

use the following conversion factors to complete the calculations that follow
4.00 flam=1.00kern 5.00 folt= 1.00kern

1.00 burb=3.00 flam 1.00 sapper= 6.00 folt

a)15.2 kern equals how many flam?

b)47.65 sapper equals how many kern?

c)0.845 flam equals how many folt?

d)one burb is equivalent to how many sapper?

The Attempt at a Solution

a) 15.2 x 4.00= 60.8 flam

b)47.65x6.00=285.9
285.9/5=57.18

c)im not sure where to begin for this one I am at work right now but i will add my own attempt when I get back home if anyone wants to give me a start that would be good.

d)for this one I am pretty sure I can do it but I have to leave work right now so I will get back to this in about 45 minutes.

 

[gneill]

You can always multiply a number by one and leave it unchanged. So set up your given equivalences as ratios that are equal to one:

\frac{4.00 flam}{1.00 kern} = 1

\frac{5.00 folt}{1.00 kern} = 1

\frac{1.00 burb}{3.00 flam} = 1

\frac{1.00 sapper}{6.00 folt} = 1

Conversions are then just a matter of successive multiplication by the appropriate ratios (or their inverses) so that the units cancel along the chain, leaving the units you want.

So, for example, for item (a) (which you already answered):

15.2 kern \times \frac{4.00 flam}{1.00 kern} = 60.8 flam

 

[davie08]

thanks for the help gneill I think I have c and d right using what you said here's my solutions to c and d.

c)0.845flam(1kern/4flam)= 0.21125 kern
0.21125kern(5folt/1kern)=1.01foltd) 1burb(3flam/1burb)=3flam
3flam(1kern/4flam)=.75kern
.75kern(5folt/1kern)=3.75folt
3.75folt(1sapper/6folt)=0.6sapper

the final answer for d would be with only one significant figure right?
also is it okay if i put brackets vs an equal sign when showing my work?

 

[gneill]

For c, you might want to check your rounding. Should be 1.06 folt.

For d, I think you want to carry 3 significant digits. 1 burb, without a decimal point, implies an "exact" number. The sig figs of the conversion constants will apply.

 

[davie08]

ya I don't know where i got 1.01 from thanks for pointing that out. that also makes sense for d because it does show 1.00.

for a number like 190 would the significant digits be 2 or 3? and another one is 30.2100 would this be 6?

 

[gneill]

http://www.usca.edu/chemistry/genchem/sigfig.htm"

 

[davie08]

thanks that gave me my answers.