- #1

James2911

- 13

- 0

## Homework Statement

Calculate Tension (Tp) and (TQ) (P is the mid point)

## Homework Equations

T - mg = ma

## The Attempt at a Solution

For Q (massless rope)

Tq - 1.9g - 0.2g - 2.9g = 5a

Tq = 5(g+a)

Tq = 5 * 10 = 50N

Given answer = 50N

(Calculation of Tension for Q is clear to me, but I am getting 2 answers for tension of P)

Answer 1 - For P (rope with mass, hence tension can't be considered equal on all points)

Tp - .1g - 2.9g = 3a

Tp = 3(g+a) = 30N

Answer 2 - For P

Tp - 1.9g - 0.1g = 2a

Tp = 2(g+a) = 20N

**The given answer is Tp = 30N**

Now here's my doubt.

Now here's my doubt.

In answer 1 - we are calculating Tension at point P. We considered the weights 0.1kg and 2.9kg and ignored that the 1.9kg weight. But I think the weight 1.9kg would apply a force 1.9g which should be considered.(Here we come up from down and include one weight (1.9kg and .1kg)

In answer 2 - we considered the weights 1.9kg and 0.1kg but didn't include 2.9kg. So, here we ignored 2.9kg like it didn't exist. But wouldn't the 2.9g exert a force? (Here we go up from down and include 2.9kg and 0.1kg(half of mass of rope)

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Out of answer 1 and 2, I consider Answer 2 i.e., 20N to be more right than the second one because, we are asked to find Tension at the midpoint. So we should just only consider the forces that are acting on it.

Please help. I've tried to find more solutions of this question online. Tq always comes out to be 50N.

But the value of Tp seems to be either 20N or 30N on different forums. Which is the correct value?

(reiteration: Tp = 30N is the given answer)