The variation of potential energy $U$ of a system is shown in the figure. The force acting on the system is best represented by:

The potential energy of a certain particle is given by $U = \frac{1}{2}\,(x^2 - z^2)$. The force on it is:

$A$ body is moved along a closed loop. Is the work done in moving the body necessarily zero? If not,state the condition under which work done over a closed path is always zero.

In a gravitational field,if the work done along paths $1, 2$ and $3$ is ${W_1}, {W_2}$ and ${W_3}$ respectively,then:

The graph of potential energy $U(x)$ versus distance $x$ is shown in the following figure. The force $F$ versus distance $x$ graph will be represented by (assume that the force is conservative):

When a conservative force does positive work on a body,