# Where to start the range?

1. Sep 17, 2009

### exparrot

I don't know if this could be considered a HW question, so please, moderators, excuse me if I'm posting in the wrong place.

Anyways, in my physics class we did a projectile lab. We had a projectile launcher that stood a few inches above the table (from a mount) and we shot the projectile horizontally. I'm now asked to calculate the initial velocity with which the ball left the launcher, but I'm a bit confused what to consider as my range. If I remember my professor correctly, the distance traveled by the ball from the launcher over the table and before going over is negligible. The range would be considered from where the table ends to where the projectle landed. That is if I understood correctly. I would appreciate anyone who's familiar with the projectile lab correct me if I'm wrong or reaffirm what I'm thinking. Thanks!

2. Sep 17, 2009

### Staff: Mentor

I'm not familiar with the lab, but I'm familiar with projectile motion. Start the calculations from where the ball left the launcher. That's where it starts dropping from.

You might even get extra credit if you compare the full equation's results with the "simplified" equation where you neglect the extra distance. How many percent difference does it make in the accuracy of the results?