IBEW Mechanical Principles and Pulleys 2

Question 1

A fixed pulley changes the direction of force but not the amount. If you pull down with 50 lbs on a fixed pulley, how much weight does it lift?

Accepted Answer

50 lbs

Answer

A fixed pulley provides no mechanical advantage — it only redirects force. 50 lbs of pull lifts 50 lbs.

Question 2

A movable pulley system has 2 rope segments supporting the load. What is the mechanical advantage?

Accepted Answer

2

Answer

Mechanical advantage = number of rope segments supporting the load = 2.

Question 3

A gear with 20 teeth meshes with a gear with 40 teeth. If the smaller gear rotates at 100 RPM, what is the speed of the larger gear?

Accepted Answer

50 RPM

Answer

Speed ratio = teeth of driven ÷ teeth of driver. 20/40 × 100 = 50 RPM.

Question 4

A lever has a 6-foot effort arm and a 2-foot resistance arm. What is the mechanical advantage?

Accepted Answer

3

Answer

MA = effort arm ÷ resistance arm = 6 ÷ 2 = 3.

Question 5

Which type of pulley system provides the greatest mechanical advantage: a single fixed pulley, a single movable pulley, or a block and tackle with 4 rope segments?

Accepted Answer

Block and tackle with 4 segments

Answer

Block and tackle with 4 rope segments: MA=4. Single movable: MA=2. Single fixed: MA=1.

IBEW - Aptitude Test Practice Test

IBEW - Aptitude Test Practice Test

IBEW Mechanical Principles and Pulleys 2