Where on a roller coaster would a car accelerate opposite to the direction of motion?

positive reinforcement? ?

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

a straight line sloped

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west