you need
  • Atwood machine, weights
First you need to consider the simplest case where the load is suspended by a thread rests.On the cargo vertically down the force of gravity Ftyazh = mg, where m - mass of the load and g - acceleration of free fall (in the world ~ 9.8 m / (s 2). Since the load is stationary, and in addition to the gravity andstrength thread tension other forces it does not apply, according to Newton's second law T = Ftyazh = mg, where T - the power of the thread tension. If the load while moving uniformly, that is, no acceleration, then T is also equal to mg according to Newton's first law.
Now let load of mass m moves down with an acceleration a.
Then, according to Newton's second law Ftyazh-T = mg-T = ma. Thus, T = mg-a.

These two simplethe case of the above, and should be used in more complex back of to determine the strength of the thread tension.
in problems of mechanics usually done important assumption that the thread inextensible and weightless. This means that the weight of the yarn can be neglectedand the thread tension force is the same over the entire length.

The simplest case of this problem - the analysis of the movement of goods in the Atwood Machine.This machine is a fixed unit, which is spanned by a thread, to which the goods are suspended two masses m1 and m2.If the masses of goods are different, the system comes into linear motion.
equations for the left and right bodies on Atwood Machine will be recorded in the form of: -m1 * a1 = -m1 * g + T1 and m2 * a2 = -m2 * g + T2.Given the properties of the thread, T1 = T2.Expressing the thread tension force T of the two equations, you get: T = (2 * m1 * m2 * g) / (m1 + m2).