Question

Part A: The sun produces 3.9 x 10^33 ergs of radiant energy per second. How many ergs of radiant energy does the sun produce in 2.45 x 10^5 seconds?

Part B: Which is the more reasonable measurement of the distance between the tracks on a DVD:

7.4 x 10^-4 mm or 7.4 x 10^4 mm? Justify your answer.

Answer 1

Whats the answer?

Answer 2

A = 3.9 x 10^33 times 2.45 x 10^5 ergs

Answer 3

first work out 3.8 * 2.45
then 10^33 * 10 ^5 = 10 ^(33+5) = 10^38

Answer 4

then combine them

Answer 5

use ur calculator to do the first part

Answer 6

Okay how do I combine them?

Answer 7

well its just

first part x 10^38

Answer 8

10X38 u mean?

Answer 9

3.8 X 2.45=9.31 what do i do next?

Answer 10

no first work out the 3.8 * 2.45
- that is the 'first part'

Answer 11

then its 9.31 x 10^38

Answer 12

thats the answer 9.31 x 10^38 ergs

Answer 13

I have allitle trouble with the 9.31 X 10^38 what does that equal?

Answer 14

I think thats what they want as the answer - its called scientific form.

its huge! it has 39 digits in it:- 931 + 36 zeroes

Answer 15

But what about the rest?

Answer 16

no Actually 3.9 X 2.45=9.555

Answer 17

so the answer is 9.55 X 10^38?

Answer 18

oh ok - my mistake 9.555 x 10^38 is correct answer

Answer 19

Thank u very much what about the part B?

Answer 20

I need an answer for the part B

Answer 21

gap between traks on DVD is very small In scientific notation this has a negative power - so for example 2x10^-4 = 0.0002

Answer 22

so which one of the 2 options in B do you think is right one?

Answer 23

7.4 X 10^-4

Answer 24

yup

Answer 25

Thank u very much can u help me with just one more?

Answer 26

sorry gotta go right now

Answer 27

okay thank u for the help