Question

Can any object have momentum even its mechanical energy is zero? explain.
Urgent!!! please help!!

Answer 1

Not always... say the PE IS -1 and its velocity is 1 m/s... then its mechanical energy is 0 but it has momentum ...ie mv!

Answer 2

Theoretically the gravitational or other potential energies of binding are defined to be negative.  The kinetic energy is always positive.

For a body that has velocity equal to escape velocity from Earth (or any planet) has a total total energy (KE + gravitational PE) zero. All the inter-planetary satellite/space craft missions use this principle.