You are Here: Home >< Maths

# Mechanics constant acceleration help watch

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
2. (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
3. (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?
4. (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
5. (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
6. (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 you cannot do that

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

It looks as though you have said you cannot do that

Find a first
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?
8. (Original post by Sayless)
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
9. (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?
10. (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?
11. (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
12. (Original post by Sayless)
meant to say speed is 10ms-1, the acceleration is 0.5
yes

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: December 3, 2014
Today on TSR

### Cambridge interviews

Find out which colleges are sending invitations

### University open days

• University of East Anglia
Fri, 23 Nov '18
• Norwich University of the Arts
Fri, 23 Nov '18
• Edge Hill University
Sat, 24 Nov '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams