A Charpy impact test is performed on a steel sample having a cross sectional area of 1 cm2. The impact test is perfomed by lifting a wedge, of 10 kg mass, to a height of 1 m. The wedge is connected to a pendulum and swings through an arc and hits the sample at the bottom of the arc. The sample breaks and the wedge continues its swing to a height of 0.5 m. The energy required to break the sample is closest to