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ENGINEERING, PPT 2025 HSC 23a

A winch is a gear system. It can be used to pull a boat out of the water and up a slipway.

Outline the function of the gears in a winch.   (2 marks)

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  • Gears in a winch increase the mechanical advantage of the system, reducing the effort needed to lift or pull a heavy load such as a boat.
  • They also increase the velocity ratio, meaning the effort moves through a greater distance than the load. Gears can additionally change the direction of the applied force.
Show Worked Solution
  • Gears in a winch increase the mechanical advantage of the system, reducing the effort needed to lift or pull a heavy load such as a boat.
  • They also increase the velocity ratio, meaning the effort moves through a greater distance than the load. Gears can additionally change the direction of the applied force.

ENGINEERING, PPT 2025 HSC 12 MC

An image of a screw jack is shown. The tommy bar is used to operate the screw jack
 

The screw jack has a pitch of 8 mm, and the force on the tommy bar is applied 400 mm from the axis of the screw.

What is the velocity ratio (VR) of the screw jack?

  1. 50
  2. 157
  3. 314
  4. 628
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\(C\)

Show Worked Solution
\(VR\) \(= \dfrac{2\pi L}{p}\)  
  \(= \dfrac{2\pi \times 400}{8}\)  
  \(= \dfrac{2513.3}{8}\)  
  \(= 314\)  

  
\(\Rightarrow C\)


♦♦♦ Mean mark 24%.

ENGINEERING, PPT 2017 HSC 20 MC

A compound lever system is shown.
 

What is the velocity ratio of this lever system?

  1. 1:1
  2. 2:1
  3. 4:1
  4. 6:1
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`D`

Show Worked Solution
  • This question is solved by splitting the compound lever system into 2 parts, ‘cutting’ it through the vertical beam, and finding the VR of both sections.
  • VR is equal to the distance of the effort over the distance of the load.
  • For the right hand side, VR=200/100=2, and for the left hand side, VR=300/100=3.
  • The total VR is equal to these multiplied together, therefore the VR is 6:1.

`=>D`


♦♦♦ Mean mark 25%.

ENGINEERING, PPT 2017 HSC 21a

Using examples, explain why gears are used in the design of vehicles.   (3 marks)

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  • Speed, rotation direction and torque can all be changed in engineering mechanisms using gears.
  • Different gear ratios with different types of gears can be combined to change direction or increase torque or speed.
  • For example, a truck cannot travel fast but it can carry tonnes of goods, whereas a performance motorcycle is unable to carry any meaningful load but can travel at high speeds.
Show Worked Solution
  • Speed, rotation direction and torque can all be changed in engineering mechanisms using gears.
  • Different gear ratios with different types of gears can be combined to change direction or increase torque or speed.
  • For example, a truck cannot travel fast but it can carry tonnes of goods, whereas a performance motorcycle is unable to carry any meaningful load but can travel at high speeds.

ENGINEERING, PPT 2022 HSC 19 MC

A gear system for a machine is shown.
 

What is the speed, in revolutions per minute (rpm), of the driven gear when the driving gear rotates at 1800 rpm?

  1. 150 rpm
  2. 450 rpm
  3. 600 rpm
  4. 1800 rpm
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`A`

Show Worked Solution
`R_(output)` `= 1800xx(text{input})/(text{auxiliary})xx(text{auxiliary})/(text{output})`  
  `= 1800xx1/3xx1/4`  
  `= 150\ text{rpm}`  

 
`=>A`


♦ Mean mark 44%.

ENGINEERING, PPT 2021 HSC 8 MC

A gear system is shown. 
 

What is the velocity ratio of this gear system?

  1. 0.3125
  2. 0.320
  3. 3.125
  4. 3.20
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`A`

Show Worked Solution
`VR` `=\ text{output teeth ÷ input teeth}`  
  `=25 -: 80`  
  `=0.3125`  

 
`=>A`

♦ Mean mark 40%.