Hi, im in grade 11 and need some help for my final exam in physics. I have read the one of the sticky posts and im not looking for someone to do my homework, just looking for some good notes that I can use to study. The first topic that I need help on is on "Dynamics" The question is on Fnet. "A person of mass 70kg is sitting on a 20kg slide. If two people are pulling her with two different ropes, find the persons acceleration. the force of person1 is 50N [E40*N] and the force of person2 is 60N [E25*S] I would like this explained to me as if you were trying to teach a 10 year old this I also need examples/notes on the following topics (I missed these class do to sickness, and I missed all the notes, tryed to get them from classmates, long story) "Sound Intesity" "Doppler Effect" and "Standing Waves". If you could explain to me these in plain english with examples, that would be of much help. Thanks.