WTMA Levers, Pulleys, and Gears 4 — Questions and Answers
Question 1: A lever with a mechanical advantage greater than 1 means:
- The effort arm is shorter than the load arm
- The load arm is shorter than the effort arm (Correct answer)
- The load equals the effort
- The fulcrum is at the load end
Correct answer: The load arm is shorter than the effort arm
When the effort arm is longer than the load arm, the mechanical advantage exceeds 1, multiplying the input force.
Question 2: A rack and pinion converts:
- Rotational motion to linear motion
- Linear motion to rotational motion only
- Rotational motion to rotational motion
- Rotational motion to linear motion (and vice versa) (Correct answer)
Correct answer: Rotational motion to linear motion (and vice versa)
A rack and pinion can convert rotational to linear motion and linear to rotational, depending on which part is driven.
Question 3: You need to raise a 500 lb engine block using a rope and pulley. Which setup requires the LEAST effort?
- One fixed pulley
- One movable pulley with one fixed pulley
- Two fixed pulleys
- A pulley system with 5 rope segments supporting the load (Correct answer)
Correct answer: A pulley system with 5 rope segments supporting the load
Five supporting rope segments give a mechanical advantage of 5, requiring only 100 lb of effort versus more in all other options.
Question 4: Gear backlash refers to:
- Excess speed in a gear train
- The slight gap between meshing gear teeth (Correct answer)
- Gears rotating in opposite directions
- The torque output of the final gear
Correct answer: The slight gap between meshing gear teeth
Backlash is the small clearance between gear teeth when they mesh, allowing for thermal expansion and lubrication.
Question 5: A bevel gear set is used to:
- Increase speed without changing direction
- Transmit rotation between parallel shafts
- Change the direction of rotation between intersecting shafts (Correct answer)
- Convert rotation to linear movement
Correct answer: Change the direction of rotation between intersecting shafts
Bevel gears transmit power between shafts that intersect at an angle, typically 90 degrees.
Question 6: If the effort arm of a lever is tripled while the load arm stays the same, the mechanical advantage:
- Stays the same
- Triples (Correct answer)
- Is halved
- Doubles
Correct answer: Triples
Mechanical advantage = effort arm ÷ load arm, so tripling the effort arm triples the mechanical advantage.
Question 7: Two pulleys connected by a belt have diameters of 4 inches and 12 inches. The smaller pulley spins at 900 RPM. The larger pulley spins at:
- 2700 RPM
- 300 RPM (Correct answer)
- 225 RPM
- 450 RPM
Correct answer: 300 RPM
Speed ratio = small diameter ÷ large diameter: 900 × (4/12) = 300 RPM.
WTMA Levers, Pulleys, and Gears 4
A lever with a mechanical advantage greater than 1 means: