The solution at revision #13616 of . This is not the current version.

Statement

2.1.49∗. A load is suspended from the free end of the thread attached to the wall and thrown over the roller. The roller is fixed on a bar of mass , which can slide along a horizontal plane without friction. At the initial moment, the thread with the load is deflected from the vertical by an angle and then released. Determine the acceleration of the bar if the angle formed by the thread with the vertical does not change during the movement of the system. What is the weight of the cargo?

 For problem 2.1.49

Solution

 Forces acting on the system
Forces acting on the system

Newton's second law of motion:

Since

From (1)

Length of the rope:

Since the rope is inextensible

From :

By dividing the equations from (1):

and using (4)

By dividing the equations from (1):

Note that: