Q 11-05-135JEE MainJEE Main 2021 (27 Jul, Shift 2)Medium
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 $E_{\text{mech}} = 8$ J, the incorrect statement for this system is: [where K.E. = kinetic energy]
Answer: (B) at $x < x_1$, K.E. is smallest and the particle is moving at the slowest speed.
K.E. $= E_{\text{mech}} - U = 8 - U$.
For $x > x_4$: $U = 6$ J, so K.E. $= 2$ J, constant. Correct.
For $x < x_1$: $U = 8$ J, so K.E. $= 0$. The particle is at rest there, not moving. Statement (2) is incorrect.
At $x_2$, $U$ is minimum, so K.E. is maximum. Correct.
At $x_3$: $U = 4$ J, K.E. $= 4$ J. Correct.
Solution by Sreeraj P, M.Sc Physics