IBEW Aptitude Test Mechanical Principles and Pulleys Questions and Answers 2

Question 1

A block-and-tackle system has 4 rope segments supporting the load. If the load weighs 400 lbs, what force must be applied (ignoring friction)?

Accepted Answer

100 lbs

Answer

With 4 supporting rope segments, the mechanical advantage is 4. Force = 400 ÷ 4 = 100 lbs.

Question 2

Which type of lever is a wheelbarrow an example of?

Accepted Answer

Second-class lever

Answer

A wheelbarrow has the load between the fulcrum (wheel) and the effort (handles), making it a second-class lever.

Question 3

Two gears are meshed together. Gear A has 20 teeth and Gear B has 60 teeth. If Gear A rotates at 180 RPM, at what speed does Gear B rotate?

Accepted Answer

60 RPM

Answer

Speed ratio is inverse of tooth ratio. Gear B speed = 180 × (20/60) = 180 × 1/3 = 60 RPM.

Question 4

Which simple machine is a screw considered?

Accepted Answer

A wedge wrapped around a cylinder

Answer

A screw is an inclined plane (wedge) wrapped in a helical path around a cylinder.

Question 5

A fixed pulley is used to lift a 200-lb load. What effort force is required?

Accepted Answer

200 lbs

Answer

A fixed pulley only changes the direction of force, not the magnitude. The effort equals the load: 200 lbs.

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