Why is This Test Answer Wrong?

Oh wow, that question seems like a high school question why is it on a post graduate test?

[quote]beachguy498 wrote:
Here we go. First convert 3000 RPM into Revolutions per Second, which is 50 RPS.

Now convert to what 1 Rev/Second is. 1/50 = .02 seconds for one Revolution.

So we have 1 Revolution = .02 seconds. The 20 degree is 20/360 or 1/18th of a Revolution. (Math is .02/18).

20 degrees = 1.111 x 10^-3 Seconds. Invert that and you get exactly 900m/second.

BG[/quote]

Surely. But that doesn’t explain why only one 900m/second answer is right, and the other 900m/second answer is wrong.

[quote]NealRaymond2 wrote:
beachguy498 wrote:
Here we go. First convert 3000 RPM into Revolutions per Second, which is 50 RPS.

Now convert to what 1 Rev/Second is. 1/50 = .02 seconds for one Revolution.

So we have 1 Revolution = .02 seconds. The 20 degree is 20/360 or 1/18th of a Revolution. (Math is .02/18).

20 degrees = 1.111 x 10^-3 Seconds. Invert that and you get exactly 900m/second.

BG

Surely. But that doesn’t explain why only one 900m/second answer is right, and the other 900m/second answer is wrong.
[/quote]

I thought that it was pretty evident that whoever was grading the test had an answer key in front of them with C being designated as the correct answer. I went through the exercise just to see if either A or B were plausible fits.

Not the first time that I’ve seen a botched test question at a college or post grad level.

BG