Calculating Compound Gears Quiz

Gears

• A pair of wheels with teeth that interlink, transferring turning motion and force to each other.
• Characteristics of gears:
  • Work together in gear trains (2 or more gears)
  • Can change the speed, force, and direction of motion
  • Alternate the direction of spin
  • Integrate with other gears, or with a linkage (e.g., sprockets)

Multiplying and Reducing Gears

• Multiplying gears: larger driving gear increases turning speed in the system
• Reducing gears: smaller driving gear decreases turning speed in the system

Mechanical Advantage (MA)

• Calculated as output force (load) / input force (force you apply)
• MA = 1 (no mechanical advantage) when input force equals output force
• Example: Justin uses a wheelbarrow to move 600 N bricks with 120 N (MA = 5)

Mechanical Advantage (MA) of Pulleys

• MA = number of pulleys in the system
• Diameter of pulleys does not affect MA

Mechanical Advantage (MA) of Screws

• MA = π (diameter of screw head) / lead (distance of one full rotation)
• Example: MA of a screw with 9mm radius and 3mm pitch is approximately 14.4

Mechanical Advantage (MA) of Inclined Planes

• MA = length of slope / height of the slope
• Example: MA of a screw with 9mm radius and 3mm pitch is approximately 3

Mechanical Advantage (MA) of Gears/Gear Trains

• MA = gear ratio (GR) = number of teeth of driven gear / number of teeth of driver gear
• Example: MA of a gear train with 30 teeth and 20 teeth is approximately 1.5

Mechanical Advantage (MA) of Other Simple Machines

• Speed ratio measures how the speed of an object is affected by a machine
• Example: inclined plane makes it possible to lift heavy objects using a smaller force, but requires moving the object over a longer distance

The Effects of Friction on MA

• Friction can reduce the efficiency of a machine and decrease MA
• One way to reduce friction is to lubricate the machine's moving parts

Calculating Pressure

• Pressure = force / area
• Example: pressure on a man's foot when a woman steps on his foot with her heel is approximately 520,000 Pa (Pascals)

Pressure in Fluids

• Hydraulic system uses a liquid under pressure to move loads
• Pneumatic system uses air under pressure to move loads
• Pascal's Law states that an enclosed fluid transmits pressure equally in all directions

Hydraulic Advantage

• Hydraulic system creates a mechanical advantage as a result of Pascal's Law on pressure
• MA is force multiplied throughout the system

Test your knowledge on compound gears, a pair of wheels with teeth that interlink to transfer turning motion and force. Learn about the characteristics of gears in gear trains, their ability to change speed, force, and direction of motion, and how they integrate with other gears.