Mechanical Aptitude Mechanical Aptitude Knowledge 5

Question 1

An electric motor nameplate reads 5 HP, 460V, 3-phase. Approximately how many amps does it draw at full load? (Use: HP × 746 / (V × 1.73 × PF), PF = 0.85)

Accepted Answer

7.0 A

Answer

I = (5 × 746) / (460 × 1.73 × 0.85) ≈ 3730 / 676 ≈ 5.5 A — closest to 5.5 A; 7.0 A accounts for efficiency losses typically making nameplate ~7 A.

Question 2

Which type of screwdriver bit is most resistant to cam-out (slipping out under high torque)?

Accepted Answer

Torx (star)

Answer

Torx bits engage the fastener with vertical walls that resist cam-out, making them ideal for high-torque applications.

Question 3

A pipe is labeled 'Schedule 80.' Compared to Schedule 40 pipe of the same nominal size, Schedule 80 has:

Accepted Answer

Thicker walls and smaller inside diameter

Answer

Higher schedule numbers mean thicker walls; the outside diameter stays the same, so the inside diameter shrinks.

Question 4

What is the primary purpose of a flywheel in an engine?

Accepted Answer

Store rotational energy to smooth out power pulses

Answer

A flywheel stores kinetic energy during power strokes and releases it between strokes to keep rotation smooth.

Question 5

Two resistors of 6 ohms and 3 ohms are connected in parallel. What is the total resistance?

Accepted Answer

2 ohms

Answer

1/R_total = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2, so R_total = 2 ohms.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Mechanical Aptitude Knowledge 5