Plant Operator Selection System Mechanical Concepts Flashcards

An inclined plane is 10 feet long and 2 feet high. Ignoring friction, what force is required to slide a 200 lb object up the ramp?

Answer: 40 lb

Mechanical advantage = length ÷ height = 10 ÷ 2 = 5; required force = 200 ÷ 5 = 40 lb.

Which property of a material refers to its ability to return to its original shape after a deforming force is removed?

Answer: Elasticity

Elasticity is the ability of a material to recover its original dimensions after the applied stress is removed.

A pressure gauge on a storage tank reads 50 PSIG. The local atmospheric pressure is 14.7 PSIA. What is the absolute pressure inside the tank?

Answer: 64.7 PSIA

Absolute pressure = gauge pressure + atmospheric pressure = 50 + 14.7 = 64.7 PSIA.

In a V-belt drive system, what is the PRIMARY reason for maintaining proper belt tension?

Answer: To prevent slippage and ensure efficient power transfer

Proper tension prevents the belt from slipping on the pulley sheaves, which would cause power loss, heat, and accelerated belt wear.

A reciprocating (piston) compressor differs from a centrifugal compressor primarily in that it:

Answer: Uses reciprocating motion to compress gas in cylinders

Reciprocating compressors use back-and-forth piston motion in cylinders with inlet and discharge valves to compress gas.

When two gears mesh together, the larger gear is called the gear and the smaller is called the pinion. If the pinion has 15 teeth and the gear has 60 teeth, what is the speed ratio (gear to pinion)?

Answer: 4:1

The pinion rotates 4 times for every 1 rotation of the large gear, giving a 4:1 speed ratio of pinion to gear (or gear runs at ¼ pinion speed).

What does the term 'specific gravity' of a liquid describe?

Answer: The ratio of the liquid's density to the density of water

Specific gravity is a dimensionless ratio comparing a substance's density to that of water (1.0), indicating whether it is lighter or heavier than water.