Push against a door that does not move. Describe the mechanical energy

Work done on the door is = 0

Mechanical energy of the person is 100%

Mechanical energy of the door is 50%.

Explanation:

Mechanical energy, M.E., is the energy an object possesses due to its position and motion. When we talk of position, the body is at rest = potential energy. In terms of motion, the body is moving = kinetic energy.

This means that M.E = potential + kinetic

Also, Work done = force × distance

For the person pushing the door, the potential of the energy stored in the person and the kinetics of pushing the door handle are all present. Therefore,  M.E of person is 100%.

But despite the doors potential energy present, there is no motion from it, which means the M.E is only half or 50%.

Also, since distance moved by the door is 0, no work is done on the door.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.