FCTC FCTC Mechanical Reasoning Principles Questions and Answers 4

Question 1

A movable pulley system lifts a 240 lb load. How much effort force is required, ignoring friction?

Accepted Answer

120 lbs

Answer

A single movable pulley provides a mechanical advantage of 2, so the effort needed is 240 ÷ 2 = 120 lbs.

Question 2

Two gears are connected via a belt and pulleys. The drive pulley has a 6-inch diameter and the driven pulley has a 3-inch diameter. If the drive pulley turns at 400 RPM, how fast does the driven pulley turn?

Accepted Answer

800 RPM

Answer

A smaller driven pulley turns faster; speed ratio = 6 ÷ 3 = 2, so 400 × 2 = 800 RPM.

Question 3

Which type of inclined plane requires the least effort force to move a 500 lb object to a height of 4 feet?

Accepted Answer

A ramp 16 feet long

Answer

A longer ramp provides greater mechanical advantage (MA = length ÷ height); a 16-ft ramp gives MA = 4, requiring only 125 lbs of effort.

Question 4

A wrench 12 inches long applies 30 lbs of force perpendicular to the handle. What is the torque produced on the bolt?

Accepted Answer

30 ft-lb

Answer

Torque = force × lever arm = 30 lbs × 1 ft (12 inches converted) = 30 ft-lb.

Question 5

A firefighter uses a crowbar (class 1 lever) with the fulcrum 6 inches from the load and the effort applied 48 inches from the fulcrum. What is the mechanical advantage?

Accepted Answer

8

Answer

MA = effort arm ÷ load arm = 48 ÷ 6 = 8.

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FCTC FCTC Mechanical Reasoning Principles Questions and Answers 4