You are Here: Home >< Maths

# M1 tension in string watch

1. for ii) of this question why isn't R = 2mg-3/5t?Attachment 507807507809 this is my diagram of it and tension acts in the same direction as r buy the mark scheme suggests that tension acts in the opposite direction. Why?? Thanks
Attached Images

2. Also for 3ii) of this question, why is the acceleration for mkg the same as a for 2mkg? Thanks
3. (Original post by coconut64)
Also for 3ii) of this question, why is the acceleration for mkg the same as a for 2mkg? Thanks
Independent of mass.
4. Ref the Tension, you have not marked a direction for tension in your diagram so far as I can see.

At the Top Left Ring, Tension acts down to the Right whilst Friction acts to the left. Possibly you are looking at force on the rough pole as you have Friction towards the Right on the LH ring and towards the Left on the RH ring

Please try to have one post for one question.
5. (Original post by Zacken)
Independent of mass.
"said the young man from Mauritius. The professor shifted uncomfortably in his seat, and sighed. He looked round at the elegantly oak-lined walls of his study, nestling in the ancient surroundings of Slaughterhouse College, Camford, and, briefly giving thanks that he had rejected the offer from that northern place (how he hated black pudding!), he mumbled the time-honoured incantation, as he so often did when faced with a promising but unformed proto-mathematician:

"Could you expand on that, please?"

He settled back in his seat, puffed on his pipe, and took a sip of port. The fire crackled; the silence deepened; the tension mounted."
6. (Original post by atsruser)
"said the young man from Mauritius. The professor shifted uncomfortably in his seat, and sighed. He looked round at the elegantly oak-lined walls of his study, nestling in the ancient surroundings of Slaughterhouse College, Camford, and, briefly giving thanks that he had rejected the offer from that northern place (how he hated black pudding!), he mumbled the time-honoured incantation, as he so often did when faced with a promising but unformed proto-mathematician:

"Could you expand on that, please?"

He settled back in his seat, puffed on his pipe, and took a sip of port. The fire crackled; the silence deepened; the tension mounted."
Oh dear, I enjoyed that acutely. It's brilliant, cracked me up at 'proto-mathematician'.
7. am I too late?
8. (Original post by Zacken)
Oh dear, I enjoyed that acutely. It's brilliant, cracked me up at 'proto-mathematician'.
I'm glad that you liked it, but I was really trying to point out that you didn't fully answer the question, and that further clarification was needed.
9. (Original post by coconut64)
Also for 3ii) of this question, why is the acceleration for mkg the same as a for 2mkg? Thanks
Consider both sides of for this particle. All the forces are proportional to the mass, and so is the RHS, so the mass can be divided away, showing that the acceleration is independent of the mass.
10. (Original post by coconut64)
Also for 3ii) of this question, why is the acceleration for mkg the same as a for 2mkg? Thanks
astruster has already explained this part but, more intuitively, think about the proportionality of acceleration in the equation

Clearly, the acceleration of an object under an applied force is proportional to the force acting on it and is inversely proportional to it's mass, meaning a greater mass will accelerate at a lower rate compared to a less mass if the applied force is the same. However, for an object in a gravitational field, the force on an object is its weight, which is proportional to its mass according to Newton's law of gravitation. This proportionality indicates the gravitational attraction of a mass itself towards other masses (or effectively towards our earth for our proposes in the question), but this proportionality is equivalent to that of the force required with respect to the resulting acceleration which is due to the equivalency of the gravitational and inertial mass. This fact comes from an experimental observation demonstrated by Galileo rather than a priori assumption and can be written as a ratio of the masses.

### 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: February 26, 2016
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '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