Slingshot Physics: Calculating Projectile Speed from a Building's Height

[Mctwist]

This one has me stuck, any help would be greately appreciated, cheers, mac


A slingshot fires a pebble from the top of a building at a speed of 14.0m/s. The building is 31.0m tall. Ignoring air resistance, find the speed with which the pebble strikes the ground when the pebble is fired (a) horizontally, (b) vertically straight up, (c) vertically straight down.

 

[tony873004]

You'll need the y-component of your initial velocities. What are they for each of those 3 scenerios?

Start with that and see how far you get.

 

[dilo247]

haha do ur physics homework urself, or dr bao will get u :@:@ haha only kiddin mate, u worked out any of the answers yet,
thanks dilo

 

[Bill Foster]

Start with the good old-fashioned equations of motion in the x- and y-directions:

$$x=x_0+v_xt$$

$$y=y_0+v_yt-\frac{1}{2}gt^2$$

$$v_y=v_{y0}-gt$$