Firefighter Aptitude Test Tuesdays – Screws
Every Tuesday I post a common question you might encounter during your firefighter aptitude test. This week we will be covering screws.
For more questions, have a look at the Firefighter Practice Tests Premium Pack. They offer over 99 practice tests and over 1500 questions.
The screw jack shown in this figure is used to lift a load over the cap by rotating the lever around. If the pitch of the screw is increased, what will be the change required in the effort on the lever?
1) Increase the lever effort
2) Decrease the lever effort
3) It will remain the same
4) Impossible to increase the pitch
The correct answer is #1, Increase the lever effort. Here is how:
The pitch of the screw is the distance moved by the spindle per revolution. By increasing the pitch, we would increase the lifting distance per revolution.
So that will increase the work to be done, and hence more effort would be needed on the lever.
What would you like me to solve next week? Leave your comment below!