John Del Latto

Partner: Daniel Landa

Experiment #6

Date Performed: 9/27/10

Date Submitted: 10/4/10

The Time of Flight of an Object Launched

Horizontally is Independent of its Initial Velocity

Objectives:

For part I of this experiment, the objective is to examine the time of flight of a ball launched horizontally with different initial velocities. For part II of this experiment, the objective is to measure the ranges of a ball launched at different angles.

Procedure:

To begin this experiment, we setup the computer software, the target pad, and the photo-gates to take measurements. For part I, we launched a ball horizontally at low and medium range onto the target pad and recorded the time of the flight. In part I, we also let a ball free fall from the same height that it was launched, and recorded the time of the free fall. In part II, we set the launcher to different angles and fired the ball so that it landed on a platform at the same height that it took off from. This allowed us to measure the range of the projectile at different angles. We measured the range at the same angles with the launcher set to short and medium range.

Uncertainties:

There are various sources of error in this experiment. One of them is the angle of the launcher with respect to the table. If it is not perfectly horizontal (0° with the horizontal) to the table during part I of the experiment, then the time of flight will not match the time of free fall. The times will also not correlate if the height of the freefall does not match the height that the projectile is launched from. Another source of error is the placement of the target pad. If the pad was not in the right place, then we would get no measurements. However, this was easily corrected by trial and error (moving the pad around until the projectile actually hit it). The photo-gates are another source of error in this experiment; if they are not calibrated correctly or if the wrong setup is entered into the computer, our measurements will be off. Finally, the most problematic aspect of this experiment is air drag. The equations we use to calculate range and time of flight work with the negligence of air friction. However, in the real world, air drag has a significant affect on the range and time of flight of a projectile. Because of this, there will always be some percent error between our measured values and our calculated values.

Conclusions:

From this experiment, I have concluded that the time of flight of a projectile rests on its vertical velocity. This is because the calculated times of flight for the short range launch, medium range launch, and vertical free fall are all the same. Also, table 1 shows that the time of flight of a projectile is about the same when it is launched horizontally (0° with the horizontal) as when it is dropped straight down; given that the vertical distance traveled is the same in both cases. I have also concluded from this experiment that an angle of 45° to the horizontal will result in a projectile traveling the greatest range. This is evident in part II, in which an angle of 45° resulted in the greatest measured and calculated range, whether the launcher was set to short or medium range.

Below is an example of a projectile motion problem: