I think its
<span>The Mechanical energy in a mechanical system is determined by adding the potential and kinetic energy together. </span>
Explanation:Photosynthesis is important because the earth and all of the creatures in the sea and land need the plants to be able to feed themselves with the help of the sun and with cellular respiration, those plants are able to take in the carbon dioxide that we give and make into oxygen with we need. there fore without them we would not be able to exist.
When a kettle is boiling you are able to see the chemical reaction, from the stem leaving the kettle, so yes
Hope this helped : )