Classical mechanicsLesson 4 of 7 in the course Linear Momentum and Collisions

Momentum and Kinetic Energy in Collisions and Explosions

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

Save course
Lesson progress
0 / 5

Your progress is kept in this browser only.Sign up to save it

Summary

This lesson introduces the main ways objects interact and the conservation principle that applies to them. Distinguishing momentum from kinetic energy is essential for classifying collisions correctly.

For objects moving along one line, momentum is p=mvp=mv, with velocity signs indicating direction. Momentum conservation applies to collisions and explosions alike. Kinetic energy, however, may change.

All flashcards

What is a closed system in collision analysis?
A chosen set of objects with negligible net external impulse during the interaction, so its total momentum is conserved.
What is an explosion?
An interaction in which one object separates into multiple pieces; stored energy can become kinetic energy.
What defines an elastic collision?
The system’s total kinetic energy is unchanged before and after the collision.
What defines a perfectly inelastic collision?
The colliding objects stick together and share one final velocity.
Why can a collision system’s momentum be conserved while its kinetic energy decreases?
Momentum conservation does not require kinetic-energy conservation; kinetic energy can become heat, sound, or deformation.

Quiz questions

  1. Two objects collide and stick together. For the same initial conditions, what is true of this perfectly inelastic collision?Answer: It produces the greatest possible loss of kinetic energy.
  2. A block slides to rest on a level surface under kinetic friction. If its stopping distance is dd, the friction coefficient is μk\mu_k, and gravitational acceleration is gg, what was its speed at the start of the slide?Answer: v=2μkgdv=\sqrt{2\mu_k g d}
  3. When can a car-and-truck system be treated as closed while analyzing their brief collision?Answer: When external forces provide negligible impulse during the collision.
  4. Large-angle scattering of alpha particles by thin gold foil supported which conclusion about atomic structure?Answer: Positive charge and most atomic mass are concentrated in a small nucleus.
  5. In a one-dimensional elastic collision, which pair of conservation laws can determine two unknown final velocities?Answer: Conservation of total momentum and total kinetic energy.

Based on University Physics Volume 1 by William Moebs, Samuel J. Ling, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

More in Classical mechanics

All Classical mechanics lessons
Classical mechanicsNewton’s Third Law, Motion, and System Boundaries5 flashcards · 5 quiz questions · 4 gamesPlay free →Classical mechanicsSimple Harmonic Motion: Spring Oscillators, Phase, and Equilibrium5 flashcards · 5 quiz questions · 4 gamesPlay free →Classical mechanicsAngular Kinematics and Acceleration in Circular Motion5 flashcards · 5 quiz questions · 4 gamesPlay free →Classical mechanicsGravitational Fields, Weight, Rotation, and Gravity Inside Spheres5 flashcards · 5 quiz questions · 4 gamesPlay free →Classical mechanicsFree-Body Diagrams: Components, Contact Forces, and Constraints5 flashcards · 5 quiz questions · 4 gamesPlay free →Classical mechanicsCommon Forces and Fictitious Forces in Newtonian Mechanics5 flashcards · 5 quiz questions · 4 gamesPlay free →