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# Mechanics AQA Question Help-Kinematics watch

1. 1) A car accelerates at 2ms^-2 from rest for 10 seconds along a straight road.
a) Find the distance travelled by the car and the speed it reaches.
b)After the 10 seconds it’s acceleration changes to 0.5ms^-2 and then remains constant for a further 5 seconds. Find the speed of the car and the total distance that it has travelled at the end of the 15 seconds.

So, for part a) - i got s= 100m & v=20ms-1, which is correct according to the back of text book.
For part b) i got v=22.5ms^-1 & s=106.25m
V=22.5ms^-1 is right according to the answers but apparently s=206.25m- so i’m off by exactly 100 & i don’t understand where i went wrong
so could someone please explain it to me
thankyou.
2. (Original post by navpahal)
So, for part a) - i got s= 100m & v=20ms-1, which is correct according to the back of text book.
For part b) i got v=22.5ms^-1 & s=106.25m
V=22.5ms^-1 is right according to the answers but apparently s=206.25m- so i’m off by exactly 100 & i don’t understand where i went wrong
so could someone please explain it to me
thankyou.
Did you not add the 100 from part (a) ??
3. (Original post by RDKGames)
Did you not add the 100 from part (a) ??

lmao thankyou i missed out such a simple step i was so confused
4. thankyouuuu !!!

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Updated: February 10, 2018
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