PLEASE I NEED 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)?

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is transformed ⇒ as it changes into other forms of energy.

Why should the wavelength scale of spectroscope be calibrated

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?