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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%.