Assistance required for following

  • Thread starter faisal
  • Start date
  • #1
faisal
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assistance required for following please

3 questions that have driven me up the wall

Homework Statement


0.5km2 is the same area as
a)5x10*6m2
b)5x10*12mm2
c)5x10*9cm2
d)5x10*13mm2


Homework Equations


10*6m=1km2


The Attempt at a Solution


0.5x10*6= 500,000 the answer is a) i don't understand what iv done wrong

q2

Homework Statement


0.04m3 is the same volume as
a)4x10*6mm3
b)40dm3
c)4x105cm3
d)4x10*2dm3

Homework Equations


in 1m3=10*9mm
1x10*9x0.04=4x10*7??

The Attempt at a Solution


the answer is a)

Homework Statement


5x10*8mm2 is the same as
a)500cm2
b)5x10-4km2
c)5m2
d)5x10-2m2
my workings
10*6mm=1m2
1/10*6=1x10-6
1x10-6x5x10*8=5x10*2
the answer is d my answer doesn't come as -2 as it should
 

Answers and Replies

  • #2
faisal
46
0
common guyz I'm dying
 
  • #3
drpizza
286
0
Your solution is correct, if there was a choice for meters squared.

You'll need to convert that to mm^s, or cm^2 in order to determine which choice is correct. Working within scientific notation makes it easier, i.e rather than .5 km^2, you could write it as .5 * (10^3 m) ^2
When you square a number with an exponent, you multiply the exponents. Thus, 10^3 squared is 10^6. Thus that equals .5 * 10^6 or in proper scientific notation, 5 * 10^5


the prefix "kilo" can be replaced with 10^3
the prefix "centi" can be replaced with 10^-2
and the prefix "milli" can be replaced with 10^-3

It might be quicker to just convert everything (the choices) to regular SI units.

Thus, something like 15 cubic millimeters would look like this
15 * (10^-3 meters)^3 = 15* 10^-9m^3 or 1.5*10^-8m^3
 
  • #4
faisal
46
0
Your solution is correct, if there was a choice for meters squared.

You'll need to convert that to mm^s, or cm^2 in order to determine which choice is correct. Working within scientific notation makes it easier, i.e rather than .5 km^2, you could write it as .5 * (10^3 m) ^2
When you square a number with an exponent, you multiply the exponents. Thus, 10^3 squared is 10^6. Thus that equals .5 * 10^6 or in proper scientific notation, 5 * 10^5


the prefix "kilo" can be replaced with 10^3
the prefix "centi" can be replaced with 10^-2
and the prefix "milli" can be replaced with 10^-3

It might be quicker to just convert everything (the choices) to regular SI units.

Thus, something like 15 cubic millimeters would look like this
15 * (10^-3 meters)^3 = 15* 10^-9m^3 or 1.5*10^-8m^3

if my methods are correcct why are all my answers wrong?
 
  • #5
Gokul43201
Staff Emeritus
Science Advisor
Gold Member
7,176
21
0.5*10^6 is not 5*10^6

when you say "the answer is x" are you talking about the choice you believe is the correct answer or are you talking about the answer given by the book. If the latter, they are all wrong. Perhaps you are looking at the wrong part of the answer list?
 
Last edited:

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