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In everyday use and in kinematics, the speed of an object is the magnitude of its velocity (the rate of change of its position); it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second, but the most common unit of speed in everyday usage is the kilometre per hour or, in the US and the UK, miles per hour. For air and marine travel the knot is commonly used.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second (approximately 1079000000 km/h or 671000000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed.

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    SA Fine Amount Incorrect for Speed?

    Good Morning Law Answers, I unfortunatly didnt notice a speed change that went from 80 to 60 and back to 80 and was fined for doing 82 in a 60 zone, which I do not dispute rules are rules. However looking into the fine amounts for listed on LawAnswers.com.au for SA and the the different tiers...
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    QLD 3 speed camera fines, one evening

    Good afternoon, I recently drove in an unfamiliar area, Lutwyche Road on the north side of Brisbane for two trips, to drop people off in the City, I returned home to Burpengary between both trips. Two weeks later I get three of these "Infringement Notice Photographic Detection Device Offences"...
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    SA Radar speed infringement

    I received a speeding infringement while travelling for business through SA. This was in a construction zone. I was speeding so accepted the fine. When trying to pay the fine online it would not accept the notice number. After calling the SA police I was told the fine was withdrawn, a few days...
  4. M

    QLD Speed Camera Incorrect Location Pic.

    Received an infringement notice / photo stating that I was doing 68 kph in a 60 zone on a road in Brisbane Queensland. That road is a 60 kph zone. But photo on the infringement notice is a section of road about 2km's further along. Different street name, different suburb, and is a 70kph zone...
  5. S

    NSW Hand Held Speed Gun - Will I get a fine????

    Just wondering if i will receive a fine in the mail if the cop did not pull me over. I was in a school zone doing between 40 - 50. I really can't remember! I slowed down before I saw the cop because I knew I was speeding. I am on my P1 licence. Thanks.
  6. R

    NSW 10k over speed limit

    I received a speeding fine including 1 demerit point for going 70kmph in a 60 zone. A number of people have told me that you can challenge a fine when it is 10kmph over the speed limit as there is a tolerance to allow for innaccuracy of cameras. Is this correct?
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    QLD Peculiar Speed Camera Fines

    Hi. I recently received four speed camera fines within the space of two days, from driving through Airport Link toll road in Brisbane (from the same camera). This caught me largely by surprise as I have never received a speeding fine or driving violation (currently on final year of P2 license...
  8. M

    VIC Excessive Speed - No recorded speed, Good Driver History, P Plater.

    Hey, I'm Seeking Advice as to whether or not I have a case appealing the infringement in court. I am a green p-plater holding a licence from July 2014 with 1.25 demerit point loss for speeding 89 in an 80 zone, and a warning for 56 in a 50 zone - what I assume to be relatively good driver...
  9. L

    QLD Contesting Speed Fine - Borderline 10% Speedo Variance

    Hi All, I received a speeding ticket in the mail for going 123km/h in a 110km/h zone after blindly passing a hidden trailer camera. I drive a car from the 80's, which, from factory, has a speedo variance of +/- 10% the actual speed. I can't recall sitting that high above the limit, and by...