PLEASE HELP A forensic investigator notes that an 8g lead bullet melted completely upon impact with a doorframe. Assuming the bullet was fired at room temperature (~20 OC), what would be the minimum muzzle velocity of the gun (in other words, how fast was the bullet traveling)?

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.