Final answer:
When calculating the speed of a rifle bullet, use kinetic energy instead of momentum.
Step-by-step explanation:
When calculating the speed of a rifle bullet, it is appropriate to use kinetic energy rather than momentum. Kinetic energy is the energy of an object due to its motion, and it can be calculated using the formula KE = 1/2mv^2, where m is the mass and v is the velocity. In this case, the speed of the bullet can be calculated by finding its kinetic energy using the given mass (0.0250 kg) and velocity (550 m/s).