Physics Chain?

Question

A chain consisting of five links, each of mass 0.125 kg, is lifted vertically with a constant acceleration of a = 2.2 m/s2. Find the magnitude of the force that link 3 exerts on link 2.

I know the formula is F= M A

so F= 2.2 * 0.125 but what does it matter what link it is in the chain? and whats the magnitude?

Answer 1

> what does it matter what link it is in the chain?

It does matter, because each link is lifting all of the links underneath it. This means that the top link (Link 1) is lifting 4 links; while Link #2 is lifting only 3 links, so it doesn't need to pull as hard.

Consider the bottom 3 links as a single entity, of mass m = 3(0.125kg) = 0.375 kg. There are two forces acting on this "entity":

Downward force F_g due to gravity:
F_g = mg

Upward force F_up, due to link 2 pulling on Link 3.

So:
Net force = F_up – F_g = ma (minus sign because they act in opposite directions)

Or:
F_up – mg = ma

F_up = m(a+g)
= (0.375kg)(2.2m/s² + 9.8m/s²)

> whats the magnitude?
"magnitude" just means the "amount" of the force without taking into account its direction.

Answer 2

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