If a point particle slides down an inclined plane with friction, its mechanical energy:
A) Remains constant
B) Increases
C) Decreases
D) Becomes zero
E) Doubles
IMAT 2026 · Question 51
Q51 - Work, energy and power
Pinned
The correct answer is C) Decreases.
Friction is a non-conservative force: it does negative work and turns part of the mechanical energy (kinetic + potential) into heat. So the mechanical energy decreases as the particle slides down. The total energy is still conserved, because the “lost” part becomes internal energy.
A) Incorrect: Mechanical energy stays constant only without friction.
B) Incorrect: To increase, something would have to do positive work on the particle.
C) Correct: Friction converts mechanical energy into heat.
D) Incorrect: Friction removes energy gradually. Nothing says it all disappears.
E) Incorrect: Doubling would require energy to be added, not removed.
Replies 0
No other replies yet.
Log in to reply.