# Projectile Motion ball is thrown upward

1. Oct 13, 2014

### creynaud

1. The problem statement, all variables and given/known data
A ball is thrown upward at an angle of 30° to the horizontal and lands on the top edge of a building that is 20 m away. The top edge is 5.0 m above the throwing point. How fast was the ball thrown?

2. Relevant equations
xcos30
ysin30

3. The attempt at a solution
Im not sure what I am supposed to do considering there is no velocity given

2. Oct 13, 2014

### ShayanJ

Well, the problem is asking for the initial velocity, so its very natural that the initial velocity is not given to you!!!

Just take a look at the equations you have at hand and see which one has only one unknown, taking into account the data given in the problem.

3. Oct 14, 2014

### dean barry

So the ledge coincides with the apex of the parabola
You also need the value for g (gravitational acceleration)
Youll be working on the vertical vector of the launch velocity first

4. Oct 14, 2014

### Staff: Mentor

Not necessarily. The projectile can land at the given spot after passing through its zenith.

5. Oct 14, 2014

### nasu

This assumption is not implied by the text and is not necessary.

6. Oct 15, 2014

### dean barry

Beyond me, sorry.
Dean