As shown in the figure. "Tower crane" is a common lifting equipment used on construction sites. OC section for the balance arm, C end is equipped with a counterweight body, the mass of 1t, OD section

As shown in the figure. "Tower crane" is a common lifting equipment used on construction sites. OC section for the balance arm, C end is equipped with a counterweight body, the mass of 1t, OD section is called the crane. (1) tower crane base area, increasing the tower and ground contact area, reducing the pressure on the ground; base mass is to reduce the center of gravity, increase the stability of the tower.

And the mass is also larger.

(2) according to the principle of balance of the lever F1L1 = F2L2, F1, L1 must be L2 the smaller the F2 the larger, the pulley block in the process of moving between the two points of E, D, in the E point when L2 is the smallest, so in the E point when the mass of the largest can be lifted, known as the C end of the counterweight body mass m=1t=1000kg, the maximum mass of the lifting m',

pulley block At E, by the lever balance principle: mg?OC = m'g?OE,

that is: 1000kg × 9.8N/kg × 12m = m'× 9.8N/kg × 15m

that m'=800kg.

(3) the tower crane on the weight of the work done by the work W = mgh = 6000N × 15m = 9 × 104J,

"Tower crane" is the largest mass of the weight of the body.

The power of the work done by the "tower crane" on the object P=

W

t

=< td style="border-bottom:1px solid black;padding-bottom:1px;font-size:90%">9×104J

30s

=3000W.

Therefore, the answer is: (1) increase the force area, reduce the pressure; lower the center of gravity, increase stability.

(2) The maximum mass of the object that can be lifted by the crane is 800kg.

(3) The power of the work done by the crane on the object is 3000W.

(4) The power of the work done by the crane on the object is 3,000W.

(5) The power of the work done by the crane on the object is 3,000W.