How many degrees the lead bullet will heat up if its velocity at the moment of impact on the earth shaft = 150 m / s.

How many degrees the lead bullet will heat up if its velocity at the moment of impact on the earth shaft = 150 m / s. Assume that 75 percent of the kinetic inergy goes to heating the bullet.

Given: V (speed of the lead bullet at the moment of impact on the earth shaft) = 150 m / s; η (the percentage of kinetic energy that goes to heat the lead bullet) = 75%.

Reference values: С (specific heat capacity of lead) = 140 J / (kg * ºС).

The change in the temperature of a lead bullet can be determined from the equality: η * Ek = Q and η * 0.5 * m * V ^ 2 = C * m * Δt, whence Δt = η * 0.5 * V ^ 2 / C.

Let’s calculate: Δt = 0.75 * 0.5 * 150 ^ 2/140 = 60.27 ºС.

Answer: The lead bullet will heat up to 60.27 ºС.