# The slingshot question

1. Nov 20, 2007

### 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.

2. Nov 20, 2007

### tony873004

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

3. Nov 21, 2007

### 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

4. Nov 21, 2007

### Bill Foster

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

$$x=x_0+v_xt$$

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

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