# Motion of Ball Rolling Off Table

• Feb 7th 2010, 09:23 AM
mrsplant
Motion of Ball Rolling Off Table
A pingpong ball rolls off a table with the speed of 2ft/sec. The table is 3.5 ft high.
1. Determine the point at which the ball hits the floor, and find its speed at the instant of impact.
2. Find the angle between the path of the ball and the vertical line drawn through the point of impact.

I know how to find the time and speed of the ball hitting the floor, but I'm confused by how to find the exact point at which it hits the floor, as well as the angle!

Thanks
• Feb 7th 2010, 10:30 AM
Henryt999
Quote:

Originally Posted by mrsplant
A pingpong ball rolls off a table with the speed of 2ft/sec. The table is 3.5 ft high.
1. Determine the point at which the ball hits the floor, and find its speed at the instant of impact.
2. Find the angle between the path of the ball and the vertical line drawn through the point of impact.

I know how to find the time and speed of the ball hitting the floor, but I'm confused by how to find the exact point at which it hits the floor, as well as the angle!

Thanks

Set the y-axis as the height and the x-axis as the axis away from the table.
The motion in the x-axis is constant since it has no acceleration.
If you know the time it takes for the ball to fall to the ground then you can calculate the distance it travels in the x-axis. Then you have a inpact point. with coordinates from the point it rools of. Now all you need to do is make a triangel. The base is the distance in the x-axis and y-axis is the 3.5ft. And the angle is simple trigonometri. calculate the speed at impact in x-axis and y axis and there is your angle
Can you take it from here?