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

# Mechanics tension modelling question watch

1. From WJEC Specimen paper. "One end A of a light inextensible rope AB, of length 08 m, is attached to the top of a fixed vertical pole. [...] What assumption does the word 'light' enable you to make in your solution." I put that 'light' means we can say the string has no mass, so we do not have to take into account the weight of the rope etc.

The mark scheme, however, says that this means tension is constant throughout the rope. Is this an error with the mark scheme? If not, can someone explain why 'light' means that tension is constant? Thanks!
2. (Original post by osamabinfishing)
From WJEC Specimen paper. "One end A of a light inextensible rope AB, of length 08 m, is attached to the top of a fixed vertical pole. [...] What assumption does the word 'light' enable you to make in your solution." I put that 'light' means we can say the string has no mass, so we do not have to take into account the weight of the rope etc.

The mark scheme, however, says that this means tension is constant throughout the rope. Is this an error with the mark scheme? If not, can someone explain why 'light' means that tension is constant? Thanks!
What you have said is correct, but the mark scheme has taken this one step further. Consider a rope that is not light and is being used to suspend a mass. The top of the rope will then be supporting the mass of the rope plus the suspended mass while the bottom of the rope will be supporting only the suspended mass. As a result, the tension in the rope will vary along its length. By contrast, for a light rope we may assume constant tension throughout the rope.

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: March 1, 2018
Today on TSR

### He broke up with me because of long distance

Now I'm moving to his city

### University open days

1. University of Bradford
Wed, 25 Jul '18
2. University of Buckingham
Psychology Taster Tutorial Undergraduate
Wed, 25 Jul '18
3. Bournemouth University
Clearing Campus Visit Undergraduate
Wed, 1 Aug '18
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

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