Mechanical Comprehension Flashcards

A screw has 20 threads per inch. How far does it advance per complete revolution?

Answer: 0.05 inches

Advance per revolution = 1 ÷ threads per inch = 1 ÷ 20 = 0.05 inches.

Which simple machine is essentially an inclined plane wrapped around a cylinder?

Answer: Screw

A screw is an inclined plane (ramp) wound helically around a cylindrical shaft.

If a 10 kg box is pushed across a floor with a coefficient of kinetic friction of 0.3, what is the friction force? (g = 10 m/s²)

Answer: 30 N

Friction force = μ × N = 0.3 × (10 × 10) = 30 N.

In a compound pulley system with 4 rope segments supporting the load, what is the mechanical advantage?

Answer: 4

Mechanical advantage of a pulley system equals the number of rope segments supporting the load.

Which valve type is best suited for fully open or fully closed flow control, not for throttling?

Answer: Gate valve

Gate valves are designed for on/off service and should not be used for throttling as the gate can vibrate and erode.

A steel beam deflects more when a load is applied at its center than at its end because:

Answer: The bending moment is greatest at the center

A center load on a simply supported beam creates maximum bending moment at midspan, causing greatest deflection there.

What happens to the buoyant force on an object if it is submerged deeper in a fluid?

Answer: It stays the same

Buoyant force equals the weight of displaced fluid, which depends only on submerged volume, not depth.