JEE Main202127 Jul 2021Evening ShiftPhysicsWork, Power and EnergyActual
Given below is the plot of a potential energy function U ( x ) for a system, in which a particle is in one dimensional motion, while a conservative force F ( x ) acts on it. Suppose that E mech = 8 J , the incorrect statement for this system is :
Options
- Aat x > x 4 ,   K . E . is constant throughout the region.
- Bat x < x 1 ,   K . E . is smallest and the particle is moving at the slowest speed.
- Cat x = x 2 ,   K . E . is greatest and the particle is moving at the fastest speed.
- Dat x = x 3 ,   K . E . = 4   J
Correct answer
B. at x < x 1 ,   K . E . is smallest and the particle is moving at the slowest speed.
Step-by-step solution
(A) at x > x 4 ,    U = constant = 6   J K = E mech .  - U = 2   J =   constant (B) at x < x 1 ,    U = constant = 8   J K = E mech .  - U = 8 - 8 = 0   J Particle is at rest. (C) At x = x 2 , U = 0 ⇒ E mech .  = K = 8   J KE is greatest, and particle is moving at fastest speed. (D) At x = x 3 ,    U = 4   J U + K = 8   J K = 4   J