What are two ways engineer's use their understanding of KE and PE to make their designs better/safer?

Find the empirical formula of each of the following compounds. given mass or for each element in a sample of the compound 3,611 g ca; 6.389 g c1

For each of the following mixtures decide if filtering would be suitable to separate the substances. explain your answers. oil in water sugar in water sand in water chalk in water tea leaves in a cup of tea

Can someone me with questions 15 to 17 plz.