#### Solution

Fig. 2 illustrates the forces acting in the physical model. Using this information we can derive appropriate mathematical equations to describe the motion:

The forces acting on the system are shown in Fig. 2 where:

*T* = Tension in the string in Newtons

*a* = Acceleration of and in m/s^{2}

Force supporting the pulley system in Newtons

The equations of motion are:

For (i)

For (ii)

By considering these equations we can find the acceleration *a* and Tension, *T*:

Adding (i) and (ii) gives:

Thus:

Þ *a* = m/s^{2 } (iii)

But, equation (ii) above gives: . Substituting the value for *a* derived in equation (iii) gives:

Þ *T *= N