20 1 1, Xicheng district, Beijing, the examination paper of the second model of the third year of high school is pulley machinery.

n 1 & lt； N2 in 1-N2I = N2-n 1 = 100n

N 1xAO=NaxBO

X2/ 1 =(300 Newton+100 Newton)

N 1=800

N2=N 1+ 100N=900

P1:p2 = (fn1/s): (fn2/s) = Nepal: N2=8/9.

First, the problem P 1:P2 is immediately related to P=F/S, and s is a constant. In other words, just find two F values and compare them.

First, the force at the B end is 100N+300N (armor plus pulley), so the force at the A end is 800N. That is, the pressure of people on the ground is 800 N.

Then according to the condition IN 1-N2I= 100N, according to the question meaning N 1

N2-N 1= 100N

N2 = 100n+n 1 = 100n+800n = 900n

The final answer is p 1: p2 = 8/9.