A 15 g bullet is fired at a 2.1 kg wooden block which is hung at the end of 1.35 meter long string as a ballistic pendulum. the bullet strikes the block and embeds itself 10 cm into the block. the pendulum then swings up to an angle of 27.5 degrees. what is the muzzle velocity of the bullet? how much energy is transformed to thermal energy by friction between the bullet and the block?