Mechanics constant acceleration help

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Sayless
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#1
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#1
I'm stuck on the following question:

A car travels a distance of 100 metres along a straight line in 20 seconds. The car was initially at rest and travelled with uniform acceleration.
A) Find the acceleration of the car.
B) Find the speed of the car when it has travelled 100 metres.

I have the distance 100 metres, time 20 seconds, initial velocity 0ms^-1 but i dont know which formula to put them in in order to get the acceleration of the car. Please help me I don't have long to do it :/ thanks <3
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TenOfThem
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(Original post by Sayless)
I'm stuck on the following question:

A car travels a distance of 100 metres along a straight line in 20 seconds. The car was initially at rest and travelled with uniform acceleration.
A) Find the acceleration of the car.
B) Find the speed of the car when it has travelled 100 metres.

I have the distance 100 metres, time 20 seconds, initial velocity 0ms^-1 but i dont know which formula to put them in in order to get the acceleration of the car. Please help me I don't have long to do it :/ thanks <3
You have
s
u
t
and need
a

There is only one SUVAT that uses these
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Sayless
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(Original post by TenOfThem)
You have
s
u
t
and need
a

There is only one SUVAT that uses these
I got 0.25ms^-2 for a) and 5ms^-1 for b) is that a correct calculation?
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TenOfThem
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(Original post by Sayless)
I got 0.25ms^-2 for a) and 5ms^-1 for b) is that a correct calculation?
Not what I got

Can you show working
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Sayless
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(Original post by TenOfThem)
Not what I got

Can you show working
s=100
t=20
u-0
velocity = 100/20 = 5ms^-1
5-0/20 = 0.25ms^-2
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TenOfThem
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(Original post by Sayless)
s=100
t=20
u-0
velocity = 100/20 = 5ms^-1
5-0/20 = 0.25ms^-2

What formulae did you use

It looks as though you have said  v = \dfrac{s}{t} you cannot do that


Find a first
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Sayless
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(Original post by TenOfThem)
What formulae did you use

It looks as though you have said  v = \dfrac{s}{t} you cannot do that


Find a first
what about this suvat equation
s=ut +1/2at^2
s=0x20 +1/2a x 20^2
100=1/2a x 400
1/4=1/2a
0.50ms^2 = a

is that correct?
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TenOfThem
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(Original post by Sayless)
what about this suvat equation
s=ut +1/2at^2
s=0x20 +1/2a x 20^2
100=1/2a x 400
1/4=1/2a
0.50ms^2 = a

is that correct?
yes

Now use v=u+at to get v
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Sayless
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(Original post by TenOfThem)
yes

Now use v=u+at to get v
I got 0+0.50x20 = 10ms^-1 so speed is 0.50 ms^-1 is that right?
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TenOfThem
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(Original post by Sayless)
I got 0+0.50x20 = 10ms^-1 so speed is 0.50 ms^-1 is that right?
No

Why have you turned your 10 into 0.5?
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Sayless
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(Original post by TenOfThem)
No

Why have you turned your 10 into 0.5?
meant to say speed is 10ms-1, the acceleration is 0.5
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TenOfThem
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(Original post by Sayless)
meant to say speed is 10ms-1, the acceleration is 0.5
yes
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