Speed is the rate of change of displacement with respect to its surrounding. Since the speed of a body is irrespective of its direction, therefore it is a scalar quantity.

Natural uranium as found in the Earth's crust is a mixture largely of two isotopes:uranium-238 (U-238), accounting for 99.3% and uranium-235 (U-235) about 0.7%. The isotope U-235 is important because under certain conditions it can readily be split, yielding a lot of energy.

always derives gravitational energy

The nuclear force (or nucleon - nucleon interaction or residual strong force) is the force between protons and neutrons, subatomic particles that are collectively called nucleons. The nuclear force is responsible for binding protons and neutrons into atomic nuclei.