Help on SM1: Forces please - solved

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jadonim
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#1
Working on a question for Stats and Mechanics Year 1 Chapter 10;

Two particles A and B have masses 2m and 3m respectively. The particles are attached to
the ends of a light inextensible string. Particle A is held at rest on a smooth horizontal table.
The string passes over a small smooth pulley which is fixed at the edge of the table. Particle
B hangs at rest vertically below the pulley with the string taut, as shown in the figure above.
Particle A is released from rest. Assuming that A has not reached the pulley, find
(a) the acceleration of B and the tension in the string, (6)
(b) the magnitude and the direction of the force exerted on the pulley by the string. (5)
(Hint, the pulley is pulled directly in to the table at a 45◦ angle, so use some trigonometry
to find out how much of the tension acts in that direction)

Cheers
Last edited by jadonim; 8 months ago
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mabutt1
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(Original post by jadonim)
Working on a question for Stats and Mechanics Year 1 Chapter 10;

Two particles A and B have masses 2m and 3m respectively. The particles are attached to
the ends of a light inextensible string. Particle A is held at rest on a smooth horizontal table.
The string passes over a small smooth pulley which is fixed at the edge of the table. Particle
B hangs at rest vertically below the pulley with the string taut, as shown in the figure above.
Particle A is released from rest. Assuming that A has not reached the pulley, find
(a) the acceleration of B and the tension in the string, (6)
(b) the magnitude and the direction of the force exerted on the pulley by the string. (5)
(Hint, the pulley is pulled directly in to the table at a 45◦ angle, so use some trigonometry
to find out how much of the tension acts in that direction)

a) Found myself with acceleration for B being 9.8 and therefore the tension being 0N... Am I wrong?

Cheers
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mabutt1
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(Original post by mabutt1)
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I have done many of these. There is not enough information to have an exact value for the tension.
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mabutt1
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(Original post by mabutt1)
I have done many of these. There is not enough information to have an exact value for the tension.
I have never been taught how to do part b. You probably have a different exam board to me. Hope this helps.
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jadonim
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(Original post by mabutt1)
I have never been taught how to do part b. You probably have a different exam board to me. Hope this helps.
cheers mate, helps a lot 👍
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