You are Here: Home >< Maths

# SUVAT question query?

Announcements Posted on
Last day to win £100 of Amazon vouchers - don't miss out! Take our quick survey to enter 24-10-2016
1. 14. A particle moving in a straight line with constant acceleration takes 3s and 5sto cover two successive distances of 1m. Find the acceleration

I got these 2 formulas

1=3u+4.5a
2=8u+32a

Why cannot i use this method to find a?

1=3u+4.5a *8
2=8u+32a *3

I've tried doing it this way but get the wrong answer and instead have to work it out by substitution and am wondering why this method doesnt work and when to know when to use which method
2. (Original post by ErniePicks)
14. A particle moving in a straight line with constant acceleration takes 3s and 5sto cover two successive distances of 1m. Find the acceleration

I got these 2 formulas

1=3u+4.5a
2=8u+32a

Why cannot i use this method to find a?

1=3u+4.5a *8
2=8u+32a *3

I've tried doing it this way but get the wrong answer and instead have to work it out by substitution and am wondering why this method doesnt work and when to know when to use which method
You need to multiply both sides by 8 and 3.
3. (Original post by Zacken)
You need to multiply both sides by 8 and 3.
sorry i have another suvat question

for this question

A train stops at two stations P and Q which are 2km apart. It acceleratesuniformly from P at 1ms-2 for 15s and maintains a constant speed for a timebefore deceleration uniformly to rest at Q. If the deceleration is 0.5ms-2 findthe time for which the train is travelling at a constant speed

I calculated that during the first acceleration stage the V=15 m/s so for the constant speed phase i got

U=15
V=15
A=0
T=?

Why cannot i use v=u+at to find t? is it because 0 doesnt count as constant acceleration? (i mean it's constantly zero..)
4. (Original post by ErniePicks)

U=15
V=15
A=0
T=?

Why cannot i use v=u+at to find t? is it because 0 doesnt count as constant acceleration? (i mean it's constantly zero..)

You can use it, 0 is constant acceleration. It's just that your equation is useless.

It's like asking "why can't I use 1 + 1 = 2 to find t?"; 1 + 1 = 2 is a true equation but it's useless to the specific scenario at hand.
5. (Original post by ErniePicks)

Why cannot i use v=u+at to find t? is it because 0 doesnt count as constant acceleration? (i mean it's constantly zero..)
if a=o then v=u+at is just v=u since it is the same as v=u+0t and anything times zero is still zero

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: May 30, 2016
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:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams