Union Pacific Mechanical Aptitude Test
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1.
A wrench is used to loosen a bolt. If the wrench handle is made longer
while the same amount of force is applied, what happens to the torque
produced?
A. It decreases
B. It remains the same
C. It increases
D. It becomes zero
Rationale: Torque equals force multiplied by the perpendicular
distance from the pivot point. Increasing the wrench length increases
that distance, so the same force produces greater torque.
2.
,Which tool is primarily designed to measure the outside diameter of a
shaft accurately?
A. Pipe wrench
B. Micrometer
C. Crowbar
D. Chisel
Rationale: An outside micrometer is specifically designed for precise
measurement of external dimensions such as shaft diameters. It
provides much greater precision than a standard ruler or tape
measure.
3.
A gear with 20 teeth drives a gear with 40 teeth. Compared with the
driving gear, the driven gear will rotate:
A. Twice as fast
B. At the same speed
C. At half the speed
D. Four times as fast
Rationale: Gear speed is inversely proportional to the number of teeth
when two gears mesh. Because the driven gear has twice as many
teeth, it rotates at half the speed while providing greater torque.
,4.
What is the primary purpose of lubrication in a mechanical system?
A. Increase friction
B. Increase electrical resistance
C. Reduce friction and wear
D. Increase component temperature
Rationale: Lubricants create a separating film between moving
surfaces, reducing direct metal-to-metal contact. This decreases
friction, heat generation, and wear.
5.
A 12-volt electrical circuit has a resistance of 6 ohms. According to
Ohm's law, how much current flows?
A. 0.5 ampere
B. 2 amperes
C. 6 amperes
D. 72 amperes
Rationale: Ohm's law states that current equals voltage divided by
resistance. Therefore, 12 ÷ 6 = 2 amperes.
6.
, Which instrument is commonly used to measure electrical voltage,
current, and resistance?
A. Tachometer
B. Torque wrench
C. Feeler gauge
D. Multimeter
Rationale: A multimeter combines several electrical measurement
functions, commonly including voltage, current, and resistance. It is a
fundamental troubleshooting instrument for electrical systems.
7.
What is the main purpose of a bearing?
A. Increase friction between surfaces
B. Prevent all movement
C. Support moving components while reducing friction
D. Increase the weight of an assembly
Rationale: Bearings support shafts and other moving components
while allowing controlled movement with relatively low friction.
Proper bearing operation is important for preventing excessive heat
and wear.
8.
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1.
A wrench is used to loosen a bolt. If the wrench handle is made longer
while the same amount of force is applied, what happens to the torque
produced?
A. It decreases
B. It remains the same
C. It increases
D. It becomes zero
Rationale: Torque equals force multiplied by the perpendicular
distance from the pivot point. Increasing the wrench length increases
that distance, so the same force produces greater torque.
2.
,Which tool is primarily designed to measure the outside diameter of a
shaft accurately?
A. Pipe wrench
B. Micrometer
C. Crowbar
D. Chisel
Rationale: An outside micrometer is specifically designed for precise
measurement of external dimensions such as shaft diameters. It
provides much greater precision than a standard ruler or tape
measure.
3.
A gear with 20 teeth drives a gear with 40 teeth. Compared with the
driving gear, the driven gear will rotate:
A. Twice as fast
B. At the same speed
C. At half the speed
D. Four times as fast
Rationale: Gear speed is inversely proportional to the number of teeth
when two gears mesh. Because the driven gear has twice as many
teeth, it rotates at half the speed while providing greater torque.
,4.
What is the primary purpose of lubrication in a mechanical system?
A. Increase friction
B. Increase electrical resistance
C. Reduce friction and wear
D. Increase component temperature
Rationale: Lubricants create a separating film between moving
surfaces, reducing direct metal-to-metal contact. This decreases
friction, heat generation, and wear.
5.
A 12-volt electrical circuit has a resistance of 6 ohms. According to
Ohm's law, how much current flows?
A. 0.5 ampere
B. 2 amperes
C. 6 amperes
D. 72 amperes
Rationale: Ohm's law states that current equals voltage divided by
resistance. Therefore, 12 ÷ 6 = 2 amperes.
6.
, Which instrument is commonly used to measure electrical voltage,
current, and resistance?
A. Tachometer
B. Torque wrench
C. Feeler gauge
D. Multimeter
Rationale: A multimeter combines several electrical measurement
functions, commonly including voltage, current, and resistance. It is a
fundamental troubleshooting instrument for electrical systems.
7.
What is the main purpose of a bearing?
A. Increase friction between surfaces
B. Prevent all movement
C. Support moving components while reducing friction
D. Increase the weight of an assembly
Rationale: Bearings support shafts and other moving components
while allowing controlled movement with relatively low friction.
Proper bearing operation is important for preventing excessive heat
and wear.
8.
