well this problem is killing me and ive spent a good 3 hours or so on it and still have no real results. This is the problem The 4.00-kg block in the figure View Figure is attached to a vertical rod by means of two strings. When the system rotates about the axis of the rod, the strings are extended as shown in the diagram and the tension in the upper string is 80.0 N. What is the tension in the lower cord? How many revolutions per minute does the system make? there is the picture provided what i did i realized that the sum of the forces in the x direction is equal to Tsin(theta) and that this is equal to the mass times the radial acceleration I bisected the triangle in order to make it a right triangle. from here i found the angle measures using arcsin(1/1.25)... i also found the radius by using the pythagorean thrm. to be .75m. from here i tried to solve part b but came out with a wrong answer for the y direction i know the sum of the forces is equal to cos(theta)+(-mg) these forces that ive described are only for the top string and not the bottom...im not really sure where to go from here or if im even on the right track sorry to bother you guys again im just on the verge of giving up on this problem I think the main problem is that im having troubel with finding all the forces for centripetal acceleration. ive attached a force diagram that i made. but im missing something??