3-D Kinematics Most 3-D problems can be reduced to 2-D problems when acceleration is constant Choose y axis to be along direction of acceleration Choose x axis to be along the other direction of motion Example: Throwing a baseball (neglecting air resistance) Acceleration is constant(gravity) Choose y axis up: ay=-9 Choose x axis along the ground in the direction of the throw Physics 121: Lecture 6, Pg 9Physics 121: Lecture 6, Pg 9 3-D Kinematics Most 3-D problems can be reduced to 2-D problems when acceleration is constant; Choose y axis to be along direction of acceleration. Choose x axis to be along the “other” direction of motion. Example: Throwing a baseball (neglecting air resistance). Acceleration is constant (gravity). Choose y axis up: ay = -g. Choose x axis along the ground in the direction of the throw