JEE · Physics · Work, Energy & Power doubts
15 doubts found
What does “Work” actually mean in Work, Energy & Power, and why does it matter for JEE?
energy transferred by a force: W = F·d·cosθ, where θ is the angle between force and displacement.
I keep getting “Work” questions wrong in Work, Energy & Power. What's the trap?
forgetting the cosθ — a force perpendicular to the motion does zero work.
What does “Work–energy theorem” actually mean in Work, Energy & Power, and why does it matter for JEE?
the net work done on a body equals its change in kinetic energy.
I keep getting “Work–energy theorem” questions wrong in Work, Energy & Power. What's the trap?
using only one force's work instead of the net work.
What does “Conservation of mechanical energy” actually mean in Work, Energy & Power, and why does it matter for JEE?
when only conservative forces act, KE + PE stays constant.
I keep getting “Conservation of mechanical energy” questions wrong in Work, Energy & Power. What's the trap?
applying it when friction or other non-conservative forces are present.
What does “Power” actually mean in Work, Energy & Power, and why does it matter for JEE?
the rate of doing work, P = W/t = F·v.
I keep getting “Power” questions wrong in Work, Energy & Power. What's the trap?
confusing power (how fast work is done) with energy (the total work).
What is the difference between conservative force and non-conservative force?
A conservative force (gravity, spring) stores energy recoverably and does path-independent work; a non-conservative force (friction) dissipates energy and depends on the path.
What is the difference between energy and power?
Energy is the total capacity to do work (joules); power is how quickly that work is done (watts).
What is the difference between elastic collision and inelastic collision?
Both conserve momentum; an elastic collision also conserves kinetic energy, while an inelastic one converts some KE into heat/deformation.
When do I use W = Fd cosθ in Work, Energy & Power, and what does it mean?
work done by a constant force.
When do I use KE = ½mv² in Work, Energy & Power, and what does it mean?
kinetic energy of a moving body.
When do I use P = Fv in Work, Energy & Power, and what does it mean?
instantaneous power from force and velocity.
When do I use PE = ½kx² in Work, Energy & Power, and what does it mean?
elastic potential energy stored in a stretched/compressed spring.