At the lowest level :
lift counters gravity
power counters friction.
the physics behind paper airplane is of aerodynamics
It really depends. If you are good at understanding the concepts of math and you think you can grasp the concepts of physics (which is not bad at all), then you will do fine in physics. Physics is like 50% math 50% concepts. This is my second year of physics (I am doing Physics with Calculus now) and it really isn't as bad as most people think.
theoretical physics
Physics concepts used in everyday life are apparent in electronics such as TVs and DVD players. It is also present in vehicles that move.
The study and understanding of matter and energy and their interactions.
In short Pure physics is the theoretical knowledge of concepts of physics, while applied physics is the knowledge of techniques that help to apply this theoretical knowledge to practical problems.
laser uses
Introduces children to concepts of height, gravity, physics, and fun.
Birds and airplane
I believe you mean aerodynamics.
Just download the solutions from the net
ndi ko alam..