91Ó°ÊÓ

The combination of kinetic energy, or energy of motion, and potential energy, or energy stored in a system as a result of the arrangement of its components, is known as mechanical energy.

The sum of kinetic, potential, and internal energies is always conserved.

$\mathbf{∆}\mathit{K}\mathbf{+}\mathbf{∆}\mathit{U}\mathbf{+}\mathbf{∆}{\mathit{U}}_{\mathbf{i}\mathbf{n}\mathbf{t}}\mathbf{=}\mathbf{0}$

Since external force gravity is acting on the system, so the net external force on the system is not zero so momentum will not be conserved.

Hence this statement is not true.

Since gravity is a conservative force therefore total mechanical energy (kinetic energy + potential energy) of the system will be conserved.

Hence the statement is true.

Since external force gravity is acting on the system, so the net external force on the system is not zero so momentum will not be conserved.

Since gravity is a conservative force therefore total mechanical energy (kinetic energy + potential energy) of the system will be conserved.

Therefore, Mechanical energy is conserved but momentum is not conserved

Hence the statement is not true.

Since gravity is a conservative force therefore total mechanical energy (kinetic energy + potential energy) of the system will be conserved,sothere is a change in Kinetic energy,but total energy is conserved.

Hence the statement is not true.