# M1 Tension Help!Watch

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#1
I have no flipping clue whether there is Tension in 1 direction ir 2. if it's 2 why so? it's so confusing
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#2

For Q1 there is tension going upwards but why in Q3, there is tension going in both directions???
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#3
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8 months ago
#4
(Original post by Rolls_Reus_0wner)

For Q1 there is tension going upwards but why in Q3, there is tension going in both directions???
In q1, the object is moving upwards which is why tension is in the upwards direction.

In Q3, I'm guessing the system is now in equilibrium, so that's why tension is in both directions because they're cancelling each other out.
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8 months ago
#5
(Original post by Rolls_Reus_0wner)
Notnek
In the second diagram they're showing tension acting on the pulley and in the first diagram they haven't included this force (for no particular reason but maybe it's because of what the question asks for?).

For a single particle, tension acts from the particle towards the string. It's best to focus on the forces on individual particles when doing mechanics questions. In the diagrams you're seeing forces acting on different particles which is why you're getting confused. Please ask if you're still unsure.
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#6
(Original post by Leviathan1611)
In q1, the object is moving upwards which is why tension is in the upwards direction.

In Q3, I'm guessing the system is now in equilibrium, so that's why tension is in both directions because they're cancelling each other out.
here are the questions:
Q1&3:

Notnek
Last edited by Rolls_Reus_0wner; 8 months ago
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8 months ago
#7
(Original post by Rolls_Reus_0wner)
here are the questions:
Q1&3:

Notnek
As I suspected, Q3 requires the force acting on the pulley which is why they've included this tension force in their diagram. For Q1 we don't care about forces acting on the pulley. Make sense or are you still unsure?

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8 months ago
#8
(Original post by Leviathan1611)
In q1, the object is moving upwards which is why tension is in the upwards direction.

In Q3, I'm guessing the system is now in equilibrium, so that's why tension is in both directions because they're cancelling each other out.
What you've said about Q3 doesn't make much sense to me. The two 'T's in the diagram that you're referring to are acting on different particles.
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#9
(Original post by Notnek)
What you've said about Q3 doesn't make much sense to me. The two 'T's in the diagram that you're referring to are acting on different particles.
but why is there tension going in both directions???
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8 months ago
#10
(Original post by Rolls_Reus_0wner)
but why is there tension going in both directions???
Imagine you are particle 2 in the second diagram : you would experience the string pulling you upwards to the right. That arrow is shown on the diagram.

Now imagine you are the pulley in the second diagram : you would experience the string pulling you down the slope on the left (as well as another tension which I'll ignore) which is the arrow shown in the opposite direction to the arrow showing the force acting on particle 2.

The two arrows on the diagram are forces acting on two different particles.
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#11
(Original post by Notnek)
Imagine you are particle 2 in the second diagram : you would experience the string pulling you upwards to the right. That arrow is shown on the diagram.

Now imagine you are the pulley in the second diagram : you would experience the string pulling you down the slope on the left (as well as another tension which I'll ignore) which is the arrow shown in the opposite direction to the arrow showing the force acting on particle 2.

The two arrows on the diagram are forces acting on two different particles.
Oh i get it now, thanks! For 3c, I don't get how they resolve for the pulley. how do they know what direction the pulley force is exerted. the answer says
F = 2T cos30°. No clue how to get that using the diagram
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8 months ago
#12
(Original post by Rolls_Reus_0wner)
Oh i get it now, thanks! For 3c, I don't get how they resolve for the pulley. how do they know what direction the pulley force is exerted. the answer says
F = 2T cos30°. No clue how to get that using the diagram
Watch this video and ask if you still are unsure:

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