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# M1 pulleys Watch

1. https://3b0a7b1bc87f5381e60f8f717510...%20Edexcel.pdf

question 3b, is it because the string is inextensible(doesn't stretch) thus acceleration is the same?
2. They are attached to the same rope So the speed and acceleration of B is the same as the speed and acceleration of A (of course I mean magnitude of acceleration).
Try and visualise it in your head if one of the particles was accelerating more than the other, the rope would either become slack or it would extend (yes you're right the rope is inextensible).
3. (Original post by B_9710)
They are attached to the same rope So the speed and acceleration of B is the same as the speed and acceleration of A (of course I mean magnitude of acceleration).
Try and visualise it in your head if one of the particles was accelerating more than the other, the rope would either become slack or it would extend (yes you're right the rope is inextensible).
so it's because they're also attached to the same string?
4. http://www.thestudentroom.co.uk/atta...0&d=1228425984

mark scheme says it's because its inextensible
5. (Original post by poundsoffat)
so it's because they're also attached to the same string?
It's because the string is inextensible.
6. (Original post by Zacken)
It's because the string is inextensible.
oh ok thanks
7. (Original post by poundsoffat)
https://3b0a7b1bc87f5381e60f8f717510...%20Edexcel.pdf

question 3b, is it because the string is inextensible(doesn't stretch) thus acceleration is the same?
Yes, and you can derive the result formally. If the displacement of one mass in a certain time is , and the displacement of the other is , then, since the length of the the string, , is a constant, then we must have:

i.e. - the acceleration vectors are the same size, but point in "opposite" directions (I've put "opposite" in scare quotes, since the same result applies regardless of the angle between the two sides of the string e.g. you may have one mass on a slope of a wedge, and the other hanging down its side)

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