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November 18, 2019, 05:04:39 pm

Author Topic: Why am I getting this wrong?  (Read 489 times)  Share 

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YellowTongue

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Why am I getting this wrong?
« on: June 19, 2015, 02:44:18 pm »
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A bus traveling north along a straight toad at 60km/h slows down uniformly and takes 5.0s to stop.

 Calculate the magnitude of its acceleration in km/h/s


So using the formula for acceleration;

Acceleration=v-u/time takes
                 =0-60/5
                 =-12

However, the book says that the magnitude is +12, not negative. I figured that the answer should be negative, seeing as the bus is slowing down, not speeding up Why is my answer incorrect?
                 
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Kel9901

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Re: Why am I getting this wrong?
« Reply #1 on: June 19, 2015, 03:23:40 pm »
0
A bus traveling north along a straight toad at 60km/h slows down uniformly and takes 5.0s to stop.

 Calculate the magnitude of its acceleration in km/h/s


So using the formula for acceleration;

Acceleration=v-u/time takes
                 =0-60/5
                 =-12

However, the book says that the magnitude is +12, not negative. I figured that the answer should be negative, seeing as the bus is slowing down, not speeding up Why is my answer incorrect?
                 
'magnitude' means just the number/size and not the direction. hence 'magnitude' is always positive (or zero) and 12 is the right answer.
s=change in displacement for physics
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