TalentLens Mechanical Comprehension 4

Question 1

A flywheel stores energy by rotating at high speed. What physical property determines how much energy it can store for a given RPM?

Accepted Answer

Moment of inertia

Answer

Rotational kinetic energy = ½Iω², so a higher moment of inertia stores more energy at the same angular velocity.

Question 2

A pipe has water flowing through it. If the pipe develops a small hole, in which direction does the water spray?

Accepted Answer

Perpendicular to the pipe wall

Answer

Water pressure acts equally in all directions; a hole lets water escape perpendicular to the pipe wall under that pressure.

Question 3

Two gears mesh together. Gear A has 15 teeth and turns clockwise. What direction does Gear B turn?

Accepted Answer

Counterclockwise

Answer

Meshed gears always rotate in opposite directions, so if A turns clockwise, B turns counterclockwise.

Question 4

A car engine produces 200 ft-lbs of torque at 3000 RPM. What is its approximate horsepower?

Accepted Answer

114 HP

Answer

HP = (Torque × RPM) / 5252 = (200 × 3000) / 5252 ≈ 114 HP.

Question 5

A bolt is tightened with a torque wrench. Which change would require less force to achieve the same torque?

Accepted Answer

Using a longer wrench

Answer

Torque = Force × arm length; a longer wrench increases the moment arm, requiring less force for the same torque.

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