In the Charpy impact test of Figure 2 the pendulum (mass 20 kg concentrated at the striker, arm R = 0.80 m) is released from 120° and, after breaking the notched specimen, swings up to 70° (both angles measured from the vertical through the pivot). The specimen is 10 mm × 10 mm with a 2 mm deep notch. Neglect friction. Determine (a) the energy absorbed by the specimen and (b) the impact strength based on the area below the notch (answers in J and J/mm^{2}).