A 6.0-g lead bullet traveling at 300 m/s penetrates a wooden block and stops. If 50 percent of the initial kinetic energy of the bullet is converted into thermal energy in the bullet, by how much does the bullet's temperature increase? The specific heat of lead is 128 J/kg · K.)

Question

Quizplus · Accepted Answer

First, we need to find the initial kinetic energy of the bullet:

KE = 1/2mv^2
KE = 1/2(0.006 kg)(300 m/s)^2
KE = 270 J

Next, we need to find how much of that energy was converted into thermal energy:

Heat energy = 0.50(270 J)
Heat energy = 135 J

Now we can use the formula for specific heat to find the change in temperature:

Heat energy = mCΔT
135 J = (0.006 kg)(128 J/kg·K)(ΔT)
ΔT = 1.8 K

Therefore, the bullet's temperature increases by 1.8 degrees Celsius, which is answer choice B.

A 60-G Lead Bullet Traveling at 300 M/s Penetrates a Wooden