# What is the difference between the two position time graphs? [closed]

I have: an object starts from rest and moves with a uniform acceleration of 10m/s² for 5 seconds it then uniformly retards at 10 m/s² to again come to rest in next 5 seconds its position time graph will be? (Answer: Option 3)

(Image)

But, the object is retarding later. Won't the slope of the graph go down? Also, using the equation of motion (s=ut + 1/2at² ) both have the same distances i.e., 125m. Isn't options 1 the answer?

## closed as off-topic by John Rennie, Jon Custer, Kyle Kanos, user191954, YashasOct 26 '18 at 13:14

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## 1 Answer

Option 1 has two problems 1) is not quadratic as the equation 2) the position goes back to zero, it means not that is just decelerating to stop, rather that it is moving backwards, and with constant speed, because the graph is linear. The answer is 3, look at your equation, it is a quadratic. In the first half a is positive so it is pointing upwards, in the second half is negative, so it is pointing downwards. And the position grows in both halves.