Straddling a Line

Two blocks today dove into projectile motion and two blocks delved deeper into vector operations and non-perpendicular vectors. B and C Blocks began their discussion of projectile motion and we started with basic characteristics of this type of motion and spent time focusing on projectiles launched horizontally. Projectiles can be thought of objects in free fall that are given a little bonus - a horizontal velocity. Remember that whatever happens in the horizontal direction is independent of the party going on in the vertical plane and vice versa. So, the components of the motion can be analyzed independently using our familiar kinematics formulas. For motion in the x-direction, the velocity (in the absence of air resistance) remains constant, because there is no net external force acting in that direction to accelerate the object. Motion in the y-direction is accelerated by gravity. Everything we talked about and practiced for an object being dropped or tossed straight up into the air applies to the vertical motion of a projectile. Also, remember that the initial velocity in the vertical direction for a horizontal projectile is 0 m/s. Tomorrow, we'll finish up that chat and work problems with this type of projectile before adding another twist - what do you do with a projectile launched at an angle?

E and F Blocks reviewed vector resolution and working with non-perpendicular vectors. The most attention was given to those non-perpendicular beasts, because they are a handful to work with. Read the problem closely and carefully draw your vector diagram. Don't be afraid to draw the first vector, then draw a nice coordinate plane at the tip of this guy. Then, draw the second right at the tip of the first vector, right at the origin of the grid exactly as if the first vector wasn't there at all. Do that for every vector in the problem. Break down each vector into it's x- and y-components and pay attention to what trig function is used to determine each. Then, make you list of Σx and Σy, making sure the signs of each vector you add to the lists have the proper sign. Now, it's a matter of adding everybody up and making that final, blessed right triangle and getting the magnitude and direction of the resultant. Tomorrow, E Block will start discussing projectile motion and F Block will conduct a lab investigation focusing on horizontally-launched projectiles.