Answer:
The answer is radio waves
Yes, that's a true statement.
The slope of a distance-time graph is speed. When speed is zero,
the slope of the graph is zero, and that's a horizontal line.
The object is not accelerating
Answer:
Kinetic energy cannot be negative
potential energy is a reference dependent quantity and it can be positive as well as negative both
Since potential energy is defined only for conservative force so it can not be found for friction force
Explanation:
Kinetic energy of an object is given by the formula

here we know that
m = mass of object that can not be negative
v = speed of the object and since its square is given here so it can not be negative
so Kinetic energy is always positive
potential energy is given as the energy due to the virtue of the position of object
so it is

so potential energy is a reference dependent quantity and it can be positive as well as negative both
Since potential energy is defined only for conservative force so it can not be found for friction force
Friction is used to refer to forces that resist relative motion, in general,whereas viscosity refers specifically to resistive forces that occur between layers of a fluid when fluids attempt to flow. Fluid friction is the force that resists the movement of a solid object through a fluid(liquid or gas). Sky divers falling down through the sky experience a type of fluid frictioncalled air resistance.