Tower Crane

​
w
c
70
Tower cranes are used at major construction sites to raise loads up to 120 tons. A tower crane consists of a central tower with two arms holding a fixed and a mobile counterweight. The operator moves the mobile counterweight to balance the load.

Details

Suppose the arms have a mass of 100 tons
(
w
a
)
, the lengths of the short and long arms are 56 m and 84 m, and that the center of mass is in the middle at 14 m to the right of the center of the tower. The fixed and mobile counterweights weigh 100 tons and 120 tons
(
w
f
and
w
m
). The normal force and the weight of the tower do not generate any torque. Let
w
c
be the weight of the load.
Then the position of the mobile can be calculated from
x=
1
120
(84
w
c
+14×100-56×100
).
The example is taken from H. C. Ohanian and J. T. Markert, Physics for Engineers and Scientists, Volume 1, 3rd ed., W. W. Norton & Co Inc (np), 2007.

External Links

Weight (ScienceWorld)
Torque (ScienceWorld)

Permanent Citation

Enrique Zeleny
​
​"Tower Crane"​
​http://demonstrations.wolfram.com/TowerCrane/​
​Wolfram Demonstrations Project​
​Published: December 8, 2010