Answer:
the correct answer is reduce friction
Answer:
Explanation:
Given
mass of bullet 
speed of bullet 
bullet is stopped by building and heat produced is shared between building and bullet
Kinetic Energy of bullet is converted into Thermal energy
Kinetic Energy of bullet 


So 315.06 J of Energy is converted in to thermal energy
Writing the acceleration as a function of time:
a(t) = 1 + 3√t
Integrating acceleration, we obtain velocity:
v(t) = t + 2(t)^(3/2) + c;
object at rest so velocity at t = 0 is 0 so c = 0.
v(t) = t + 2(t)^(3/2)
Integrating velocity to obtain an equation for displacement:
d(t) = t²/2 + 4/5 t^(5/2) + c
Applying limits from t = 0 to t = 9
d = 9²/2 + 4/5 9^(5/2)
d = 234.9 m