2
\$\begingroup\$

The question is:

enter image description here

The answer is:

enter image description here

My question is how did he get the 100 (highlighted)?

Source:

PPI PE Power Reference Manual, 4th Edition – Comprehensive Reference Manual for the Closed-Book NCEES PE Exam

Publisher : PPI, A Kaplan Company; Fourth edition (January 31, 2021)

ISBN-10 : 1591267838

ISBN-13 : 978-1591267836

by John A. Camara PE

\$\endgroup\$
2
  • \$\begingroup\$ Isn’t there a frequency provided somewhere? \$\endgroup\$ May 13, 2021 at 12:55
  • \$\begingroup\$ Or simply ignore the slight error in assumptions \$\endgroup\$ May 13, 2021 at 13:19

1 Answer 1

5
\$\begingroup\$

That 100 pops up for the omega. With small approximation I would say that you have a 16.7 Hz system :) one of my favorite ;), the supply of a Swiss, German, Austrian, Swedish railway. 2 * pi * 16.6667 Hz = 104.7 rad/s. (thanks @user2233709)

Otherwise it is just a good round number without physical explanation (I do not think it is easy to find a system with 15.915 Hz of fundamental).

Note: that 100 confirmed by the "100 rad/s" used one line below.

\$\endgroup\$
1
  • 1
    \$\begingroup\$ Looks plausible +1 for analysis \$\endgroup\$ May 13, 2021 at 13:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.