Again, I am studying for a test, using a list of testable questions from the instructor. One of them is in the section on orthogonal projections.

A block rests on an incline tilted 30degrees from the horizontal. Gravity exerts a force of one newton on the block. What COMPONENT of gravity moves the block along the incline.

What the hell are they talking about? If they gave me some vectors and magnitutes, I could calculate this out, so I''m not really sure what they are looking for here. Anybody know

gravity only works downwards. so draw the gravity vector from the center of mass straight down. then draw a right triangle with one leg parallel to the line of direction of motion of the block. use pythagoris to calculate the component of gravity in the direction of movement. b/c the block can''t accelerate straight downwards you have to find only the component of gravity working parallel to the object''s motions.

it''s the same thing you do for independance of x and y velocities. are you sure this is a test and not homework?

-me

I don''t know about other colleges, but here, homework is never taken up, just used for getting ready for tests. We actually got a sheet of testable questions from the instructor, because the average of the class as a whole on the last test was like 65%. I got an 85% (I know, still sucks), and I need to get an A on this test and the next to pass with an A and keep my average at 3.7 (aiming for 3.8 so I can get in Phi Kappa Phi). Nope, not homework. This book we''re using just doesn''t go into detail about the questions it asks. It explained orthogonal projections, and then asked this with no other explanation.

coolio, i was just curious. anyway, did my answer help?

-me