Chapter 4, Problem 4.59PP

Lacks are installed in rivers to allow boats to pass safely around a dam and through the associated change in water level. The doors of the lock must hold back the water as the boat passes from one level to the next. In Fig. 4.57, the rightmost pair of doors is shown separating

3.5 m

I

I

Left pair of

Right pair of

doors open

doors closed

Figure 4.57

the high side, at a depth of $6$ m, from the low side at a depth of $3.5m$. The lock is $8$ m wide. Calculate the resulting forces on this pair of doors, and draw a free-body diagram of this pair of doors showing the opposing pressure distributions.