Plz help difference between closed system and open system?

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.

Match each type of lever with the correct diagram. 1. first-class 2. third-class 3. second-class

A10 kg shark swimming at 5m/s swallows an absent-minded 0.5 kg fish that is originally at rest. what is the speed of the large fish after eating the smaller fish?