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ENGINEERING, PPT 2018 HSC 21c

The self-driving vehicle has a mass of 1.5 tonnes and is travelling at 60 km/h.

Calculate its kinetic energy.   (3 marks)

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`208.4\ text{kJ}`

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`text{Converting km/h to m/second:}`

`v` `=60\ text{km/h}`  
  `=(60\ 000)/3600\ text{m/s}`  
  `= 16.67\ text{m/s}`  

 
`m=1.5\ text{tonnes} =1500\ text{kg}`

`KE` `=1/2mv^2`  
  `=1/2 xx 1500 xx 16.67^2`  
  `=208\ 416.675\ text{J}`  
  `=208.4\ text{kJ}`  

ENGINEERING, PPT 2021 HSC 6 MC

A train has a total mass of 400 tonnes. It accelerates from rest to a speed of 25 m/s.

What is the kinetic energy of the train at the speed of 25 m/s?

  1. `125 × 10^(3)\ text{J}`
  2. `250 × 10^(3)\ text{J}`
  3. `125 × 10^(6)\ text{J}`
  4. `250 × 10^(6)\ text{J}`
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`C`

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Using 1 tonne = 1000 kg:

`KE` `= 1/2 xx mxxv ^2`  
  `=0.5xx400\ 000 × 25^2`  
  `=125\ 000\ 000`  
  `=125 xx 10^6\ text{J}`  

 
`=>C`