Turn on thread page Beta
 You are Here: Home >< Maths

Got first part can't get second watch

1. A train is uniformly retarded from 35 m/s to 21 m/s over a distance of 350m. Calculate
A) The retardation
b) The total time taken under this retardation to come to rest from a speed of 35m/s

(Letts A level mathematics)

i got first part

v = 21
u = 35
s = 350
a = ?

21² = 35² + 700a
a = 441-1225/700

= -1.12 ms-2

The second part i cannot seem to get, i'm using the formula

s = ut + 0.5at²

350 = 35t + (0.5)(1.12)(t²)

350 = 35t + 0.56t²

0 = 0.56t²+35t-350

bang that in the quadratic formula and you get...
can anyone help?
2. (Original post by thewebmaster)
A train is uniformly retarded from 35 m/s to 21 m/s over a distance of 350m. Calculate
A) The retardation
b) The total time taken under this retardation to come to rest from a speed of 35m/s

(Letts A level mathematics)

i got first part

v = 21
u = 35
s = 350
a = ?

21² = 35² + 700a
a = 441-1225/700

= -1.12 ms-2

The second part i cannot seem to get, i'm using the formula

s = ut + 0.5at²

350 = 35t + (0.5)(1.12)(t²)

350 = 35t + 0.56t²

0 = 0.56t²+35t-350

bang that in the quadratic formula and you get...
can anyone help?
S= 350 doesn't apply to this part.

Use v=u+at with u=35, v=0, and your value for a.

Aitch
3. (Original post by thewebmaster)
A train is uniformly retarded.....
I don't do Mechanics so I can't answer your question but at that part

Turn on thread page Beta

Related university courses

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: July 2, 2005
Today on TSR

Edexcel C3 Maths Unofficial Markscheme

Find out how you've done here

1,119

students online now

Exam discussions

Poll
Useful resources

Make your revision easier

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

Create your own Study Planner

Never miss a deadline again

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE