📚 Topic Summary
In a perfectly inelastic collision, objects stick together after colliding. This means that kinetic energy is not conserved, as some of it is converted into other forms of energy like heat and sound. However, momentum is conserved. To solve problems, remember to use the conservation of momentum to find the final velocity, then calculate the initial and final kinetic energies to determine the amount of kinetic energy lost during the collision.
The key equations are:
- 🔍 Conservation of Momentum: $m_1v_1 + m_2v_2 = (m_1 + m_2)v_f$
- 💡 Kinetic Energy: $KE = \frac{1}{2}mv^2$
🧠 Part A: Vocabulary
Match the term with its definition:
| Term |
Definition |
| 1. Perfectly Inelastic Collision |
A. Energy of motion |
| 2. Kinetic Energy |
B. A collision where objects stick together |
| 3. Conservation of Momentum |
C. Total momentum remains constant in a closed system |
| 4. Velocity |
D. The rate at which an object changes its position |
| 5. Mass |
E. A measure of an object's resistance to acceleration |
(Answers: 1-B, 2-A, 3-C, 4-D, 5-E)
✍️ Part B: Fill in the Blanks
In a perfectly inelastic collision, objects ______ together after the impact. ______ is conserved, but ______ energy is not. The lost kinetic energy is often converted into ______ and ______. To find the final velocity, we use the principle of conservation of ______.
(Answers: stick, momentum, kinetic, heat, sound, momentum)
🤔 Part C: Critical Thinking
Explain, in your own words, why kinetic energy is not conserved in a perfectly inelastic collision. Where does the "lost" energy go? Give a real-world example of such a collision.