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diff --git a/213/CH10/EX10.11/10_11.sce b/213/CH10/EX10.11/10_11.sce
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+//To find work done and efficiency
+clc
+//Given:
+p=10,d=50,D2=60,R2=D2/2,D1=10,R1=D1/2 //mm
+W=20*1000 //N
+mu=0.08,mu1=mu
+//Solution:
+//Calculating the helix angle
+alpha=atan(p/(%pi*d)) //radians
+//Calculating the force required at the circumference of the screw to lift the load
+phi=atan(mu) //Limiting angle of friction, radians
+P=W*tan(alpha+phi) //N
+//Calculating the torque required to overcome friction at the screw
+T=P*d/(2*1000) //N-m
+//Calculating the number of rotations made by the screw
+N=170/p
+//When the load rotates with the screw:
+//Calculating the work done in lifting the load
+W1=T*2*%pi*N //Work done in lifting the load, N-m
+//Calculating the efficiency of the screw jack
+eta1=tan(alpha)/tan(alpha+phi)*100 //%
+//When the load does not rotate with the screw:
+//Calculating the mean radius of the bearing surface
+R=(R1+R2)/2 //mm
+//Calculating the torque required to overcome friction at the screw and the collar
+T=(P*d/2+mu1*W*R)/1000 //N-m
+//Calculating the work done by the torque in lifting the load
+W2=T*2*%pi*N //Work done by the torque in lifting the load, N-m
+//Calculating the torque required to lift the load, neglecting frition
+T0=(W*tan(alpha)*d/2)/1000 //N-m
+//Calculating the efficiency of the screw jack
+eta2=T0/T*100 //%
+//Results:
+printf("\n\n When the load rotates with the screw, work done in lifting the load = %d N-m.\n",W1)
+printf(" Efficiency of the screw jack, eta = %.1f %c.\n",eta1,"%")
+printf(" When the load does not rotate with the screw, work done in lifting the load = %d N-m.\n",W2)
+printf(" Efficiency of the screw jack, eta = %.1f %c.\n\n",eta2,"%")
+\ No newline at end of file