TalentLens Mechanical Comprehension 4 โ Questions and Answers
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?
- Weight only
- Moment of inertia (Correct answer)
- Material hardness
- Surface area
Correct answer: Moment of inertia
Rotational kinetic energy = ยฝIฯยฒ, 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?
- Along the direction of flow
- Opposite to the direction of flow
- Perpendicular to the pipe wall (Correct answer)
- Downward only due to gravity
Correct answer: Perpendicular to the pipe wall
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?
- Clockwise
- Counterclockwise (Correct answer)
- It oscillates
- Direction depends on gear size
Correct answer: Counterclockwise
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?
- 57 HP
- 114 HP (Correct answer)
- 200 HP
- 600 HP
Correct answer: 114 HP
HP = (Torque ร RPM) / 5252 = (200 ร 3000) / 5252 โ 114 HP.
Question 5: A bolt is tightened with a torque wrench. Which change would require less force to achieve the same torque?
- Using a shorter wrench
- Using a longer wrench (Correct answer)
- Using a lighter wrench
- Applying force closer to the bolt head
Correct answer: Using a longer wrench
Torque = Force ร arm length; a longer wrench increases the moment arm, requiring less force for the same torque.
Question 6: Which arrangement of springs produces the greatest combined stiffness?
- Two springs in series
- Two springs in parallel (Correct answer)
- A single spring
- Series and parallel are equivalent
Correct answer: Two springs in parallel
Springs in parallel add their spring constants (k_total = k1 + k2), giving greater stiffness than either alone or in series.
Question 7: A heavy casting is being hoisted by a crane. What force acts in addition to the object's weight that the crane cable must support when acceleration is upward?
- Friction force
- Inertial force from acceleration (Correct answer)
- Magnetic force
- Air resistance only
Correct answer: Inertial force from acceleration
When accelerating upward, the cable must support both the object's weight and the extra force F = ma needed to accelerate it.
TalentLens Mechanical Comprehension 4
A flywheel stores energy by rotating at high speed.
What physical property determines how much energy it can store for a given RPM?