Question

A 0.09-kg lead bullet traveling 182 m/s strikes an armor plate and comes to a stop. If all of the bullet's energy is converted to heat that it alone absorbs, what is its temperature change

Answer 1

Answer: Δθ = 127.4 K

Explanation: by using the law of conservation of energy, the kinetic energy of the bullet equals the heat energy on the plate.

Kinetic energy of bullet = mv²/2

Heat energy = mcΔθ

Where m = mass of bullet = 0.09kg, v = velocity of bullet = 182 m/s, c = specific heat capacity of lead bullet = 130 j/kgk

Δθ = change in temperature

mv²/2 = mcΔθ

With 'm' on both sides of the equation, they cancel out each other, hence we have that

v²/2 = cΔθ

v² = 2cΔθ

Δθ= v²/2c

Δθ = (182)²/2×130

Δθ = 33124/260

Δθ = 127.4 K