Answer:
The correct answer is:
between kinetic energy and elastic potential energy.
In fact, the total mechanical energy of the system is given by:
where
is the elastic potential energy, with k being the spring constant and x being the compression/stretching of the spring, and
is the kinetic energy, with m being the mass of the toy and v being its speed.
When the spring is compressed, the elastic potential energy U is maximum (since x is maximum), and the kinetic energy is zero(since the speed is zero). As the spring is released, the elastic potential energy U decreases (because x decreases), and the kinetic energy K increases (since the speed of the toy v increases).
Step-by-step explanation: