# As physics % error help urgent pleaseWatch

#1
Hi,

1. for a cube of length (5.0+0.2)cm and mass (500+1)g calculate:
a) the percentage error in length
b)the percentage error in mass,
c)the percentage error in volume
d) density
e) the percentage error in density.

thanks,
Megan
0

4 years ago
#2
Percentage uncertainty=(absolute uncertainty/measured value)*100

Should be obvious for the a and b.

Volume=l*w*h.
When you're multiplying or dividing you have to add percentage uncertainties. Say the percentage uncertainty you calculated for length in a was x. Therefore the percentage uncertainty in the volume would be x+x+x.
Density=m/v
If the percentage uncertainty in the mass was y and the percentage uncertainty of the volume you calculated above was z then as you are dividing, same rule applies as before, you add the two percentage uncertainties together y+z.
0
#3
(Original post by J_T_)
Percentage uncertainty=(absolute uncertainty/measured value)*100

Should be obvious for the a and b.

Volume=l*w*h.
When you're multiplying or dividing you have to add percentage uncertainties. Say the percentage uncertainty you calculated for length in a was x. Therefore the percentage uncertainty in the volume would be x+x+x.
Density=m/v
If the percentage uncertainty in the mass was y and the percentage uncertainty of the volume you calculated above was z then as you are dividing, same rule applies as before, you add the two percentage uncertainties together y+z.
is the percentage error the same as the percentage uncertainty?? coz the questions asks for percentage error.
0
#4
also I can't figure out which one is absolute uncertainty.. I find it confusing
0
#5
It's okay I managed to work it out. Thanks for the help anyway.
0
4 years ago
#6
(Original post by Megan_90)
is the percentage error the same as the percentage uncertainty?? coz the questions asks for percentage error.
Yeah same thing.
(Original post by Megan_90)
also I can't figure out which one is absolute uncertainty.. I find it confusing
It's the +/- thing after the measured value.
0
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