Projectiles!

Today was projectiles launched at an angle day for all blocks - some getting their first bite at the information, others getting some review and more practice. Horizontally-launched projectile are a little easier to work with since we have only 1/2 of a parabola to work with and we know that v_i,y will be 0 m/s. That goes out the window for many projectiles, such as balls thrown through the air or missiles launched at a target. Some of the initial velocity is in the x-direction and some is in the y-direction, and you need to find those values and use them appropriately in your analyses. Most often, the x-component of the initial velocity will be found through the cosine function and the y-component through the sine function. So, for a problem where a projectile was launched at 20 m/s at an angle of 30°, you would see me write on the board:


v_x = 20 m/s(cos 30°)
v_i,y = 20 m/s(sin 30°)

right off the bat. Then, just make sure to use the proper velocity component when you work in the x- or y-directions. Another helpful trick is to break the parabola in two. This can make solving for time in the air simple. Solve for time for one-half of the parabola and then multiply times two to get full time in the air. Then, with that time, finding horizontal range is super simple (v_x = Δx/t). Different groups have different problems that they are working on tonight, and we will check over them tomorrow before moving forward. If more practice is needed, we'll take the time to do that. C Block will be doing a lab on horizontally-launched projectiles and some groups may dip toes in relative motion, depending on quickly we move through our projectiles review. Test on Friday and the Chapter 3 review sheet is up on Edline. Then - Forces!