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### AuthorTopic: Why am I getting this wrong?  (Read 530 times) Tweet Share

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#### YellowTongue

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##### Why am I getting this wrong?
« on: June 19, 2015, 02:44:18 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?

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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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