= 4. A rectangular workpiece has the following original dimensions: 2a: = 100 mm, h=25 mm, and width 20 mm. The metal has a strength coefficient of 400 MPa and strain-hardening exponent of 0.5. It is being forged in plane strain with μ=0.3. Calculate the force required when the height is reduced by 20 percent. Do not use average pressure formulas.