5.4.2 Levers and Gears

• What is a lever used for?

  Amplify force
• The fixed point around which a lever rotates is called the fulcrum
• The moment of a force is calculated as force multiplied by the distance from the pivot
• What is an example of a lever?

  Crowbar
• Order the classes of levers based on the position of the pivot relative to the force and load

  1️⃣ Class 1: Pivot between force and load

  2️⃣ Class 2: Load between pivot and force

  3️⃣ Class 3: Force between pivot and load
• Match the class of lever with its example:

  Class 1 ↔️ Seesaw

  Class 2 ↔️ Wheelbarrow

  Class 3 ↔️ Tongs
• The longer the distance from the pivot to the force, the less force needed to move the load
• What is the formula for mechanical advantage of a lever?

  $\text{MA} =$$\frac{\text{Load}}{\text{Effort}}$
• The mechanical advantage of a lever is defined as the ratio of the load force to the effort
• In Class 2 levers, the load is positioned between the pivot and the force.
• What is an example of a Class3 lever?

  Tongs
• The mechanical advantage of a lever is defined as the ratio of the load force to the effort
• What is the mechanical advantage of a lever if the load is 100N and the effort is 20N?

  5
• A mechanical advantage of 5 means the lever multiplies the applied force by a factor of 5.
• Gears transmit motion and force through interlocking teeth
• How is the gear ratio calculated?

  Teeth on driven / driving
• Arrange the following gear ratios in order from highest torque to lowest torque:

  1️⃣ 2:1

  2️⃣ 1:2
• The pivot in a lever is the fixed point around which the lever rotates.
• The moment of a force is calculated as force multiplied by the distance from the pivot
• Match the lever class with its example:

  Class 1 ↔️ Seesaw

  Class 2 ↔️ Wheelbarrow

  Class 3 ↔️ Tongs
• What happens to the force needed to move a load as the distance from the pivot to the force increases in a lever?

  Decreases
• Levers are classified into three classes based on the relative positions of the pivot, load, and force
• A mechanical advantage of 5 means the load is five times heavier than the effort required.
• How is the gear ratio calculated?

  Teeth on driven / driving
• Match the gear ratio with its effect on speed and torque:

  2:1 ↔️ Halves speed, doubles torque

  1:2 ↔️ Doubles speed, halves torque
• Steps of how gears transmit motion and force:

  1️⃣ Interlocking teeth ensure rotation

  2️⃣ Gear ratio determines speed and torque change

  3️⃣ Machines use less force at higher speeds
• What happens to speed and torque when the gear ratio is 2:1?

  Halves speed, doubles torque
• Gears in a bicycle allow riders to use less force at higher speeds by adjusting the gear ratio.
• Gears operate by interlocking teeth
• What is the formula for calculating the gear ratio?

  $\text{Gear Ratio} =$$\frac{\text{Number of teeth on driven gear}}{\text{Number of teeth on driving gear}}$
• Match the gear ratio with its effect on speed and torque:

  2:1 ↔️ Halves speed, doubles torque

  1:2 ↔️ Doubles speed, halves torque
• A gear ratio of 2:1 halves the speed
• What is the effect of a gear ratio of 1:2 on speed and torque?

  Doubles speed, halves torque
• What two components does the gear ratio compare to affect speed and torque?

  Driven gear and driving gear
• Steps to calculate the gear ratio:

  1️⃣ Identify the number of teeth on the driven gear

  2️⃣ Identify the number of teeth on the driving gear

  3️⃣ Apply the formula: $\text{Gear Ratio} =$$\frac{\text{Number of teeth on driven gear}}{\text{Number of teeth on driving gear}}$

  4️⃣ Simplify the ratio
• What does a 2:1 gear ratio mean in terms of speed and torque?

  Half speed, double torque
• A lever has three main components: the pivot, the force, and the load
• The moment of a force is calculated as Force multiplied by the distance from the pivot.
• What is the formula for calculating the moment of a force?

  \text{Moment} = \text{Force} \times \text{Distance from Pivot}</latex>
• Match the lever example with its class:

  Seesaw ↔️ Class 1

  Wheelbarrow ↔️ Class 2

  Tongs ↔️ Class 3