In the study of mechanics, particles connected by a string are commonly seen in real-life scenarios. This includes pulleys, which are often used to solve problems involving tension in connected particles. These problems help us comprehend the relationship between forces and motion, such as in situations where you need to tow a car or lift a heavy object.

When dealing with multiple particles in motion, you can either view the entire system as a whole if all the particles move in the same direction, or you can analyze each particle separately when they move in different directions. In problems with pulleys, where particles move in different directions, it is essential to consider the mass of each particle individually.

For example, let's say we have two particles, A and B, connected by a light inextensible string on a smooth surface. Particle A has a mass of 5kg, and particle B has a mass of 2kg. If a horizontal force of XN is applied to particle A in the opposite direction of B, we can determine the value of X and the tension in the string.

- To find the value of X, we can utilize Newton's second law for particle A:

- [equation 1]

- To determine the tension in the string, we need to calculate the acceleration of particles A and B using Newton's second law:

- [equation 2]

By finding the acceleration for both particles, we can eliminate the tension by combining the two equations and substituting the acceleration into one of them. This allows us to determine the value of X and the tension in the string. The figure below illustrates all the forces at play in this system.

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