Work Power Energy Questions

A particle of mass $100\text{g}$ is thrown vertically upwards with a speed of $5\text{m/s}$. The work done by the force of gravity during the time the particle goes up is:

A ball of mass $0.2\text{kg}$ is thrown vertically upwards by applying a force by hand. If the hand moves $0.2\text{m}$ while applying the force and the ball goes up to $2\text{m}$ height further, find the magnitude of the force. (Consider $g=10{\text{m/s}}^2$)

The potential energy of a $1\text{kg}$ particle free to move along the $x$ -axis is given by $V(x)=\left(\frac{x^4}{4}-\frac{x^2}{2}\right)\text{J}$. The total mechanical energy of the particle is $2\text{J}$. Then, the maximum speed (in m/s) is: