FCTC Pulleys, Gears, and Levers 4 — Questions and Answers
Question 1: A bevel gear set is used primarily to accomplish which task?
- Increase gear speed
- Transmit power between parallel shafts
- Transmit power between shafts at an angle (Correct answer)
- Reduce noise in a gear train
Correct answer: Transmit power between shafts at an angle
Bevel gears are cone-shaped and designed to transmit motion between shafts that intersect at an angle, commonly 90 degrees.
Question 2: A scissors jack on a car is an example of which simple machine principle?
- Pulley system
- Lever and screw combination (Correct answer)
- Fixed gear train
- Block and tackle
Correct answer: Lever and screw combination
A scissors jack uses a screw to force levers apart, combining lever and screw simple machines to multiply force and lift a vehicle.
Question 3: In a clock, why are gears of different sizes used together?
- To make the clock heavier
- To control different speeds for hour, minute, and second hands (Correct answer)
- To reduce friction
- To increase the clock's power source
Correct answer: To control different speeds for hour, minute, and second hands
Different gear ratios in a clock cause the hour, minute, and second hands to rotate at precise, different speeds from the same power source.
Question 4: When the effort arm of a lever is shorter than the load arm, the lever provides which of the following?
- Greater force but less speed
- Less force but greater speed and range (Correct answer)
- Equal force and speed
- Greater force and greater speed
Correct answer: Less force but greater speed and range
When the effort arm is shorter than the load arm, mechanical advantage is less than 1 — you apply more force but gain speed and distance.
Question 5: A worm gear is most commonly used to achieve which result?
- High speed transmission
- Very large gear reductions in a compact space (Correct answer)
- Parallel shaft power transfer
- Equal input and output speeds
Correct answer: Very large gear reductions in a compact space
Worm gears provide very high gear reduction ratios in a small package and are often self-locking, preventing back-driving.
Question 6: On a bicycle, shifting to a larger rear sprocket (more teeth) while pedaling causes what effect?
- Faster wheel speed with same pedaling effort
- Easier pedaling but slower wheel speed (Correct answer)
- No change in wheel speed
- Increased mechanical efficiency
Correct answer: Easier pedaling but slower wheel speed
A larger rear sprocket creates a lower gear ratio, making pedaling easier but causing the wheel to turn slower per pedal stroke.
Question 7: What does the term 'mechanical advantage' measure in simple machines?
- The speed at which a machine operates
- The ratio of output force to input force (Correct answer)
- The total energy consumed by the machine
- The weight of the machine itself
Correct answer: The ratio of output force to input force
Mechanical advantage is the ratio of the force a machine exerts on a load (output force) to the force applied by the user (input force).
FCTC Pulleys, Gears, and Levers 4
A bevel gear set is used primarily to accomplish which task?