A bullet of mass 10 g moving horizontally with a velocity of 400 ms–1 strikes a wood block of mass 2 kg which is suspended by light inextensible string of length 5 m. As a result, the centre of gravity of the block found to rise a vertical distance of 10 cm. The speed of the bullet after it emerges out horizontally from the block will be
100 ms–1
80 ms–1
120 ms–1
160 ms–1