if dbms already supports discretionary and mandatory access control is there a need for encryption?
Hope this is what you need. If not, any good search engine should get you other websites you could try. I chose this one out of the first 30 I found.
How about someone playing with a paddle-ball toy - one of those things with a rubber band, rubber ball and wood paddle. This would illustrate elastic force, centripetal force, applied force and gravity. Put her on roller skates and you would add friction and normal force. EDIT; Skate-board instead of skates! (what can I say, I'm old)
pull the door handle and push the lever back to where it should be.
