Collisions: momentum always survives, kinetic energy may not
"Collisions: momentum always survives, kinetic energy may not" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the lesson "Collisions" in Work, Energy and Power. Cart 1 runs into cart 2, which carries a spring bumper. Press Play; the crash itself runs in slow motion. Watch the total momentum and the total kinetic energy under the pictures. Total momentum is the same before and after every collision. Total kinetic energy is the same only when e = 1, and even then it dips while the bodies are squeezed. JEE Main asked 44 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Collisions in Work, Energy and Power. Change the values and watch what happens.
In JEE Main
42 shifts analysed
44 questions from Work, Energy and Power across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT § "Collisions"
- In every collision the total linear momentum of the colliding bodies is conserved, because the forces between them are internal and equal and opposite.
- In an elastic collision total kinetic energy is also conserved; in an inelastic collision part of it becomes heat, sound or deformation.
- In a completely inelastic collision the bodies stick together after impact and the loss of kinetic energy is the largest possible.
- Kinetic energy is not conserved during the brief contact itself, even in an elastic collision; the statement applies to the energy before and after.
- For one-dimensional elastic collision of m₁ (speed v₁ᵢ) with m₂ at rest: v₁f = (m₁ − m₂)v₁ᵢ/(m₁ + m₂) and v₂f = 2m₁v₁ᵢ/(m₁ + m₂).
- Equal masses in a one-dimensional elastic collision exchange velocities: the moving body stops and the struck one moves off with its speed.
- A light body striking a very heavy body at rest rebounds with nearly the same speed, while the heavy body barely moves; a heavy body hitting a light one at rest carries on almost unchanged and the light one moves off at nearly twice its speed.
- For a completely inelastic collision with m₂ initially at rest, the common velocity is v = m₁v₁ᵢ/(m₁ + m₂) and the kinetic energy lost is ½[m₁m₂/(m₁ + m₂)]v₁ᵢ².
- Each body's own kinetic energy changes in an elastic collision; it is only the total that is conserved.
Questions
3 answers
- What does the "Collisions: momentum always survives, kinetic energy may not" simulation show?
- Cart 1 runs into cart 2, which carries a spring bumper. Press Play; the crash itself runs in slow motion. Watch the total momentum and the total kinetic energy under the pictures.
- Does JEE Main ask questions from Work, Energy and Power?
- Yes. JEE Main asked 44 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Collisions" in Work, Energy and Power (Class 11 Physics).
Embed this simulation
Free, with a link back
Teaching this idea? Put the simulation on your own page or LMS with this code.