A metric trapezoidal power screw is to be designed to carry a tensile load of 125 kN while keepingthe tensile stress below 75 MPa. (b) Specify a suitable size for the screw. (c) Compute the torque required to raise and to lower the load vertically. Use a coefficient of friction of 0.15. (d) Compute the power required to raise the load a total of 4250 mm in 7.5 s. (e) Compute the lead angle for the screw. (f) Will the screw be self-locking?

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