Where does the energy go on a rough patch?
"Where does the energy go on a rough patch?" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the lesson "Conservation of mechanical energy" in Work, Energy and Power. Press Play. The block slides down a smooth 45° slope, crosses a level floor with a rough patch in the middle, and climbs the smooth slope on the far side. Watch the bars: K and V trade places, and heat grows only on the rough patch. With only gravity doing work, K + V stays at mgh. On a rough stretch K + V falls by μmg × the distance slid, and exactly that much appears as heat. JEE Main asked 44 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Conservation of mechanical energy 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 § "The Conservation of Mechanical Energy"
- If only conservative forces do work on a body, its total mechanical energy K + V stays constant.
- A body falling freely from height H has the same total energy mgH at every point: potential energy turns into kinetic energy as it falls.
- Speed at the bottom of a smooth curved track depends only on the height dropped, v = √(2gh), not on the shape of the track.
- For a bob whirled in a vertical circle on a string of length L, the minimum speed at the lowest point for completing the circle is √(5gL), and the minimum speed at the top is √(gL).
- When non-conservative forces like friction act, the loss in mechanical energy equals the work done against them: (K + V)_initial − (K + V)_final = work done against friction.
- The energy lost to friction is not destroyed; it appears mainly as heat, so total energy is still conserved.
Questions
3 answers
- What does the "Where does the energy go on a rough patch?" simulation show?
- Press Play. The block slides down a smooth 45° slope, crosses a level floor with a rough patch in the middle, and climbs the smooth slope on the far side. Watch the bars: K and V trade places, and heat grows only on the rough patch.
- 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 "Conservation of mechanical energy" 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.