You are Here: Home >< Maths

# M1 last minute help please ! Watch

1. I got 0.3125 for part c but the book has different answer. Thanks.
2. You found that total T for the journey is 96 s , 3/4 of that total T is for the time taken by the time spent on constant velocity, so that would be 72 s, 96 - 72 = 24,
We are now told that deceleration is twice as acceleration, so if we take that as ratios, it would be a ratio of 2:1 for deceleration:acceleration , therefore 24/3 gives us 8, so the time spent on deceleration would be 8s and time spent on acceleration would be 16s . Now we know that it took 8s to decelerate till rest, and we know it took 16s to accelerate to 15ms^-1 (thus deceleration is twice the magnitude of acceleration as it took half the time for it to do).
Now we split it into two separate suvat equations, using v = u + at for each, we then get :
For deceleration : 0 = 15 + 8a , rearrange to get a and we get a = - 1.875 (Negative coz its decelerating)
For acceleration : 15 = 0 + 16a, rearrange to get a we get a = 0.9375

From the results we can see that the magnitude of deceleration is twice that of acceleration. 1.875 = 2(0.9375)

Hope that helps

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: June 8, 2016
Today on TSR

### Falling in love with him

But we haven't even met!

### Top study tips for over the Christmas holidays

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• 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

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• 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

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.