Query_Asst_3

course Phy 201

Ҹn|f٦藴񇣡assignment #003

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

{jǒ士ә

Physics I

06-22-2006

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12:55:14

Query Principles of Physics and General College Physics: Summarize your solution to Problem 1.19 (1.80 m + 142.5 cm + 5.34 `micro m to appropriate # of significant figures)

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RESPONSE -->

To solve problem 1.19, first I converted all units to meters:

1.80 m

142.5 cm * (10^-2 m / 1 cm) = 1.425 m

5.34 `micro m * (10^-6 m / 1 `micro m) = .534 m

180 m + 1.425 m + .534 m = 3.76 m

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13:11:42

** 1.80 m has three significant figures (leading zeros don't count, neither to trailing zeros unless there is a decimal point; however zeros which are listed after the decimal point are significant; that's the only way we have of distinguishing, say, 1.80 meter (read to the nearest .01 m, i.e., nearest cm) and 1.000 meter (read to the nearest millimeter).

Therefore nothing below .01 m can be distinguished.

142.5 cm is .01425 m, good to within .00001 m.

5.34 * `micro m means 5.34 * 10^-6 m, or .00000534 m, good to within .00000001 m.

Then theses are added you get 1.81425534 m; however the 1.80 m is only good to within .01 m so the result is 1.81 m. The rest of the number is meaningless, since the first number itself could be off by as much as .01 m. **

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RESPONSE -->

My answer is not the same as your answer, but mine is the same as the answer listed for 1.19 at the end of the textbook.

For 142.5 cm, your conversion is .01425 m,

but I get 142.5 cm * (10^-2 m / 1 cm) = 1.425 m

For your answer, you convert 5.34 `micro m to m.

For the textbook, we are to convert 5.34 * 10^5 `micro m into meters, which is not 5.34 * 10^-6, but

(5.34 * 10^5 `micro m) * (10^-6 m / 1 `micro m), for which I get .534 m.

So, even using your original numbers:

1.80 m + 142.5 cm + 5.34 `micro m, shouldn't the correct answer be:

1.80 m + 1.425 m + (5.34 * 10^-6) = 3.23 m

instead of the 1.81 m that is listed here?

I believe your answer is correct.

.................................................

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13:11:53

University Physics #34: Summarize your solution to Problem 1.34 (4 km on line then 3.1 km after 45 deg turn by components, verify by scaled sketch).

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RESPONSE -->

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13:12:02

** THE FOLLOWING CORRECT SOLUTION WAS GIVEN BY A STUDENT:

The components of vectors A (2.6km in the y direction) and B (4.0km in the x direction) are known.

We find the components of vector C(of length 3.1km) by using the sin and cos functions.

}Cx was 3.1 km * cos(45 deg) = 2.19. Adding the x component of the second vector, 4.0, we get 6.19km.

Cy was 2.19 and i added the 2.6 km y displacement of the first vector to get 4.79.

So Rx = 6.19 km and Ry = 4.79 km.

To get vector R, i used the pythagorean theorem to get the magnitude of vector R, which was sqrt( (6.29 km)^2 + (4.79 km)^2 ) = 7.3 km.

The angle is theta = arctan(Ry / Rx) = arctan(4.79 / 6.19) = 37.7 degrees. **

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RESPONSE -->

.................................................

"

This looks good. Let me know if you have questions.

Query_Asst_3

course Phy 201

Ҹn|f٦藴񇣡assignment #003

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

{jǒ士ә

Physics I

06-22-2006

......!!!!!!!!...................................

12:55:14

Query Principles of Physics and General College Physics: Summarize your solution to Problem 1.19 (1.80 m + 142.5 cm + 5.34 `micro m to appropriate # of significant figures)

......!!!!!!!!...................................

RESPONSE -->

To solve problem 1.19, first I converted all units to meters:

1.80 m

142.5 cm * (10^-2 m / 1 cm) = 1.425 m

5.34 `micro m * (10^-6 m / 1 `micro m) = .534 m

180 m + 1.425 m + .534 m = 3.76 m

.................................................

......!!!!!!!!...................................

13:11:42

** 1.80 m has three significant figures (leading zeros don't count, neither to trailing zeros unless there is a decimal point; however zeros which are listed after the decimal point are significant; that's the only way we have of distinguishing, say, 1.80 meter (read to the nearest .01 m, i.e., nearest cm) and 1.000 meter (read to the nearest millimeter).

Therefore nothing below .01 m can be distinguished.

142.5 cm is .01425 m, good to within .00001 m.

5.34 * `micro m means 5.34 * 10^-6 m, or .00000534 m, good to within .00000001 m.

Then theses are added you get 1.81425534 m; however the 1.80 m is only good to within .01 m so the result is 1.81 m. The rest of the number is meaningless, since the first number itself could be off by as much as .01 m. **

......!!!!!!!!...................................

RESPONSE -->

My answer is not the same as your answer, but mine is the same as the answer listed for 1.19 at the end of the textbook.

For 142.5 cm, your conversion is .01425 m,

but I get 142.5 cm * (10^-2 m / 1 cm) = 1.425 m

For your answer, you convert 5.34 `micro m to m.

For the textbook, we are to convert 5.34 * 10^5 `micro m into meters, which is not 5.34 * 10^-6, but

(5.34 * 10^5 `micro m) * (10^-6 m / 1 `micro m), for which I get .534 m.

So, even using your original numbers:

1.80 m + 142.5 cm + 5.34 `micro m, shouldn't the correct answer be:

1.80 m + 1.425 m + (5.34 * 10^-6) = 3.23 m

instead of the 1.81 m that is listed here?

I believe your answer is correct.

.................................................

......!!!!!!!!...................................

13:11:53

University Physics #34: Summarize your solution to Problem 1.34 (4 km on line then 3.1 km after 45 deg turn by components, verify by scaled sketch).

......!!!!!!!!...................................

RESPONSE -->

.................................................

......!!!!!!!!...................................

13:12:02

** THE FOLLOWING CORRECT SOLUTION WAS GIVEN BY A STUDENT:

The components of vectors A (2.6km in the y direction) and B (4.0km in the x direction) are known.

We find the components of vector C(of length 3.1km) by using the sin and cos functions.

}Cx was 3.1 km * cos(45 deg) = 2.19. Adding the x component of the second vector, 4.0, we get 6.19km.

Cy was 2.19 and i added the 2.6 km y displacement of the first vector to get 4.79.

So Rx = 6.19 km and Ry = 4.79 km.

To get vector R, i used the pythagorean theorem to get the magnitude of vector R, which was sqrt( (6.29 km)^2 + (4.79 km)^2 ) = 7.3 km.

The angle is theta = arctan(Ry / Rx) = arctan(4.79 / 6.19) = 37.7 degrees. **

......!!!!!!!!...................................

RESPONSE -->

.................................................

"

This looks good. Let me know if you have questions.