Mechanical Reasoning Principles Questions and Answers Flashcards

A wheel with a radius of 2 feet is attached to an axle with a radius of 0.5 feet. If a force of 10 lbs is applied to the wheel, what force is exerted at the axle?

Answer: 40 lbs

Mechanical advantage = wheel radius ÷ axle radius = 2 ÷ 0.5 = 4, so force at axle = 10 × 4 = 40 lbs.

Two pistons are connected in a hydraulic system. Piston A has an area of 5 sq in and Piston B has an area of 25 sq in. If 50 lbs of force is applied to Piston A, what force does Piston B exert?

Answer: 250 lbs

Pascal's Law: Force B = Force A × (Area B / Area A) = 50 × (25/5) = 250 lbs.

A spring with a spring constant of 8 N/m is compressed by 0.5 m. How much potential energy is stored in the spring?

Answer: 1 J

Spring potential energy = ½ × k × x² = ½ × 8 × 0.25 = 1 J.

Which type of gear arrangement reverses the direction of rotation between the input and output shaft?

Answer: Two external spur gears meshed together

When two external spur gears mesh, they rotate in opposite directions.

A pipe carrying water narrows from a diameter of 4 inches to 2 inches. What happens to the water's velocity in the narrower section?

Answer: It quadruples

By the continuity equation, area decreases by a factor of 4 (radius halved), so velocity must increase fourfold to maintain flow rate.

A bolt is being tightened with a wrench. Applying force farther from the bolt's center will:

Answer: Increase the torque applied to the bolt

Torque = Force × Distance from pivot; increasing the distance (moment arm) increases torque for the same applied force.

If a block and tackle pulley system has 4 rope segments supporting the load, what is its mechanical advantage?

Answer: 4

In a block and tackle, mechanical advantage equals the number of rope segments directly supporting the load.