Question

1. A pole AB of length 10cm and weight 800N has its centre of gravity 4m from the end A and lies on a horizontal ground. The end B is to be lifted by a vertical force applied at B. Calculate the least force required to do this.

2. A uniform metal tube of length 5m and mass 9kg is suspended horizontally by two vertical wires attached at 50cm and 150cm respectively from the ends of the tube. Find the tension in each wire

Answer 1

1)

$$Fl=Wd\\10F=(800)(4)\\F=320\ N$$

2) The total force the wires exert on the tube is equal to its weight:

$$T_a+T_b=9(9.8)=88.29\ N\\T_a(2.5-0.5)=T_b(1.5-0.5)\\T_a=29.4\ N\\T_b=58.9\ N$$