Mechanical Reasoning Principles Questions and Answers Flashcards

If a first-class lever has the fulcrum positioned closer to the load than to the effort, what is the mechanical advantage?

Answer: Less than 1 — effort needed is greater than the load

When the fulcrum is closer to the load, the effort arm is shorter than the load arm, so mechanical advantage is less than 1 and more force is required than the load.

Two gears are meshed together. Gear A has 40 teeth and Gear B has 10 teeth. If Gear A rotates at 100 RPM, at what speed does Gear B rotate?

Answer: 400 RPM

Speed ratio is inversely proportional to gear teeth: Gear B speed equals 100 times (40 divided by 10) equals 400 RPM.

A block-and-tackle pulley system has 4 rope segments supporting the load. What is the mechanical advantage?

Answer: 4

In a block-and-tackle system, mechanical advantage equals the number of rope segments supporting the movable block.

Which screwdriver would provide the MOST torque when removing a rusted bolt?

Answer: A long-handled screwdriver

Torque equals force times distance from the pivot. A longer handle provides a greater lever arm, generating more torque with the same applied hand force.

Water flows through a pipe that narrows from a 4-inch diameter to a 2-inch diameter. What happens to the water velocity?

Answer: It quadruples

By the continuity equation, flow rate is constant. When diameter halves, radius halves, and cross-sectional area decreases by a factor of 4, so velocity must quadruple.

A hydraulic system applies 50 pounds of force on a piston with 2 square inches of area. What force is produced at a second piston with 20 square inches of area?

Answer: 500 lbs

By Pascal's Law: F2 equals F1 times (A2 divided by A1) equals 50 times (20 divided by 2) equals 500 pounds.