Ok, guys, I was hoping you could help me with basic 2 dimensional motion here. I already posted this question on a physics forum, but they got me confuzzeled as ever, so I turned to you guys. Here it is, copy and pasted

Ok, so there are two questions
#1 A ball is rolled off a table 1 meter high, and lands 4 meters away. what is the velocity for the x vector? What is the angle at which it hits the floor?

#2 A (hyperelastic? superelastic? perfectly elastic? I forgot) ball is rolled down the edge of a well at a horizontal speed of 4 m/s. The well is 4 meters deep and 0.5 meters across. What is the number of times the ball hits the wall?



2. Relevant equations
What I was thinking of was these...
1 meter = 1/2g t^2 To find the time
4 meters= velocity x (t)
I am probably wrong, but to find the angle at which the ball lands at, I will have to get the y-vector/x-vector = inverse tan. Is that correct? If so, then what should I put for the magnitude for the y vector? Should I put the final velocity, or average velocity on the y-axis?


For #2, I was planning to find the amount of time that it takes for a 4 m/s ball to cross 0,5 meters= ie. 0.5 m = 4 m/s T

Then, I would use D= 1/2 g t^2 to find how much it would drop for the first bounce. After the first bounce, with the velocity accelerating, how would i find out the amount of bounces for the rest of the distances?

Hi Picklepie

Nr. 1. The calculation to find the speed and the time is correct.
About the angle: When the ball lands it has the speed v. Written as a vector v = ( v->x , v->y)   v->y means velocity in x direction.
To get the angle between floor and the velocity vector you have to calculate  (v->y) / (v->x) = tan( angle).  This you can easily see in a sketch.
If we solve this we get: inverse tan( (v->y) / (v->x) ) = angle
The question about the velocity: The velocity vector points at a certain time exactly in the direction where it is flying. So when the ball hits the floor, the ball is flying in the direction of its velocity vector at this moment. -> You take the final velocity to calculate the velocity vector.

Nr. 2. I think it's a perfectly elastic ball. This means: No loss of energy or velocity if something like a wall is hit.
First: I won't solve this for you, but give you a hint  ;)
The key of this exercise is to split the movement into a movement in x direction and one in y direction. Is the velocity in the y- direction affected by the bounce? And the velocity/movement in x- direction? If yes: How?

If it doesn't help just ask again.

Teg's already answered - not much else to say :)

For the second one - forget completely about the collisions with the side of the well. Figure how far the ball would travel horizontally before it hits bottom. Count how many multiples of the width of the well that is....

Physics problems havn't got any more interesting by the looks of it. What level is this at?