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+// exa 9.9 Pg 272
+
+clc;clear;close;
+
+// Given Data
+d=70;// mm
+mu=0.13;// coefficient of thread friction
+mu_c=0.15;// coefficient of collar friction
+Do=90;// mm
+Di=26;// mm
+L=450;// mm
+// C-25 steel screw
+sigma_t1=275;// MPa
+sigma_c1=275;// MPa
+tau1=137.5;// MPa
+// Phosphor bronze nut
+sigma_t2=100;// MPa
+sigma_c2=90;// MPa
+tau2=80;// MPa
+pb=15;//MPa
+n=2;// factor of safety
+//screw
+sigma_ts=137.5;// MPa
+sigma_cs=137.5;// MPa
+tau_s=68.75;// MPa
+//Nut
+sigma_tn=50;// MPa
+sigma_cn=45;// MPa
+tau_n=40;// MPa
+
+p=10;// mm (for normal series square threads)
+dc=d-p;//mm
+dm=d-p/2;//mm
+t=p/2;//mm
+alfa=atand(p/%pi/dm);// degree
+fi=atand(mu);// degree
+
+K=dc/4;// mm
+C=0.25;// spring index
+sigma_y=275;// MPa
+Ac=%pi/4*dc**2;//mm.sq.
+Wcr=Ac*sigma_y*(1-(sigma_y/4/C/%pi**2/(200*10**3))*(L/K)**2);// N
+printf('\n (a) Safe Capacity of press or critical load for the screw = %.f N',Wcr)
+
+n=Wcr/(%pi*dm*t*pb);// no. of threads
+n=ceil(n);// rounding 
+h=n*p;// mm
+printf('\n (b) Height of nut, h=%.f mm',h)
+
+W=Wcr;// N
+Tf=W*dm/2*tand(alfa+fi)/1000;// N.mm (Frictional torque)
+Tc=mu_c*W/4*(Do+Di)/1000;// N.mm (Collar torque)
+T=Tf+Tc;// N.mm
+printf('\n (c) Necessary torsional moment or total torque = %.2f N.mm',T)
+// Note - answer in the textbook is wrong.