It’s burning wax. All of the other options are physical changes .
First, let's calculate the total mechanical energy when the block is at rest and the spring is compressed 5 cm:

Now, let's use this total energy to calculate the velocity when the spring is compressed by 2.5 cm:

Therefore the speed is 1.026 m/s.
Answer:
The reflected resistance in the primary winding is 6250 Ω
Explanation:
Given;
number of turns in the primary winding,
= 50 turns
number of turns in the secondary winding,
= 10 turns
the secondary load resistance,
= 250 Ω
Determine the turns ratio;

Now, determine the reflected resistance in the primary winding;

Therefore, the reflected resistance in the primary winding is 6250 Ω
Diagram A is the correct diagram