**Kinetic energy** is a form of energy that an entity or particle possesses due to its motion.

The relation between the object's mass and its speed.

KE = \frac{1}{2} mv^2

The energy contained in an object due to its location is known as potential energy.

PE = mgh , where, m - mass, g - acceleration due to gravity and h - height.

Law on energy conservation:

Energy can neither be created nor destroyed, but it can be converted from one form to another.

When the object is dropped we initially have only potential energy, which is later transformed to kinetic energy. So according to the law of conversion kinetic energy is equal to potential energy.

KE = PE

Step 1: Find an expression for the ball's velocity.

Given that

Mass of the ball m = 5 kg

Length of the rope h = 10 m

When falling through the pendulum arc, potential energy was converted to kinetic energy. According to the law of conversion, kinetic energy is equal to the potential energy.

KE = PE

\frac{1}{2}mv^2 = mgh

v^2 = 2gh

v = \sqrt{2gh}

Hence, velocity of the ball v = \sqrt{2gh}

Step 2: Determine the ball's velocity at its lowest point.

The lowest point would be 10 meters below the starting point, since the string is 10m long.

v = \sqrt{2 * (9.8 m/s^2)(10 m)}

v=\sqrt{196}

v = 14

Hence, ball's velocity at its lowest point v = 14 m/s