Finding initial velocity of a pebble thrown as a projectile

[bcotten]

Romeo tosses a pebble at Juliet's window to wake her. Unfortunately, he throws too large a pebble too fast. Just before crashing through the glass, the pebble is moving horizontally, having traveled a horizontal distance x and a vertical distance y as a projectile.

Find the magnitude of the pebble's velocity as it leaves Romeo's hand.

Find the direction of the pebble's velocity (angle above the horizontal) as it leaves Romeo's hand.

The answers need to be expressed in x y and g.


Any ideas?

 

[cristo]

This looks like a homework question. PF rules state that we must see your work before we can help you. So, do you have any ideas?

P.S. In future please post such questions in the homework forum.

 

[ranger]

Do you have any ideas? Tell us what you have done. Also it would help to draw a diagram. Since it wants the direction, you'll need to use a right triangle somewhere in your diagram.

EDIT: aw cream cheese. It took me two minutes to type this :)

 

[bcotten]

I thought it was, Vo = sqrt[((x/t)^2)+(((y-gt^2)/t)^2)] for the magnitude, but the solution does not depend on "t".

 

[bcotten]

does "moving horizontally" mean that the final velocity in the y direction is 0?

 

[highcoughdrop]

@ bcotten. I'm a total noob at this, but I'm going to guess that moving horizontally means that the pebble is at the apex of the projectile motion. I'm guessing that the time = v(initial)/g.