Officer Aptitude Rating (OAR) Test 2025 – 400 Free Practice Questions to Pass the Exam

To determine the correct method for calculating RPM (revolutions per minute) for a wheel with projection rods, it is essential to understand the relationship between the number of contacts and the function of the projection rods. In this scenario, dividing the contacts per minute by the number of projection rods gives a clear understanding of how many revolutions each rod contributes per minute.

Projection rods interact with the contacts in a manner where each rod corresponds to a certain portion of the revolutions. By dividing the total number of contacts by the number of rods, you can ascertain how many times each rod will complete a rotation in one minute, thereby accurately calculating the wheel's RPM.

Other methods, such as multiplying contacts by the number of rods, adding, or subtracting the number of rods from total contacts, do not appropriately reflect the actual relationship between contacts and the rods regarding RPM. They fail to yield a result that accurately represents the rotational speed of the wheel in terms of the functioning mechanism of the projection rods.