The sum of potential and kinetic energies in the particles of a substance is called energy. true or false

False

Explanation:

This sentence is the description of the mechanical energy.

In this sense, the mechanical energy of a body or a system is that which is obtained from the speed of its movement (kinetic energy) or its specific position (potential energy), in order to produce a mechanical work.

That is to say: The mechanical energy involves both the kinetic energy and the potential energy (which can be elastic or gravitational, for example).

In addition, it should be noted that mechanical energy is conserved in conservative fields and is a scalar magnitude.

Therefore:

The sum of potential and kinetic energies in the particles of a substance is called  Mechanical Energy

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.