Justin Geeslin

Eng Physics I - M 1:00

Experiment Five – Projectile Motion


  1. Introduction

This experiment, like its predecessor, deals with gravity’s affect on an object’s acceleration. In this experiment, a ball follows an inclined path downward through a photogate and off the edge of a table. The velocity within the photogate is measured and its position from the edge of the table to the floor is predicted.

  1. Procedure

The setup includes an incline preceding a photogate for which to roll a ball through. When the ball travels down the incline through the photogate, the photogate will provide a velocity reading to the computer. After the ball passes through the photogate, at the end of the ramp it should be allowed to fall off the edge of the table. Release the ball a total of ten times. The data should be as follows:


Trial

Velocity (m/s)

1

1.46

2

1.46

3

1.46

4

1.46

5

1.58

6

1.58

7

1.73

8

1.58

9

1.58

10

1.58


After the trial runs are complete, record your maximum and minimum velocity. Find the average velocity. Measure the height of the table from which the ball, once through the photogate, was allowed to fall. Obtain the predicted impact point by finding t. To find t, Use the formula:

t = - (2y/g)1/2


Then, to calculate the predicted Impact Point multiply t by the average velocity. The Max and Min impact point distance can be found in the same way. For the Max multiply t by the Maximum Velocity. For the Min multiply t by the Minimum Velocity. The data should be as follows:





Maximum Velocity

1.73 m/s

Minimum Velocity

1.46 m/s

Average Velocity

1.55 m/s

Table Height

0.94m

Predicted Impact Point

0.68m

Minimum Impact Point Distance

0.64m

Maximum Impact Point Distance

0.76m

Actual Impact Point Distance

0.61m



Questions

  1. One’s predictions must be based on a range of measurements if it is based on experimental data because there may be other factors that come in to play.

  2. Yes, our actual point of impact was between our max and min.

  3. The velocity may most likely vary due to the ball receiving acceleration from other sources than gravity. For example, in one run the ball may have received an accelerating push from the person who released the ball. This would affect the ball’s velocity by the time it passes through the photogate.

  4. Air resistance would affect the flight path of the ball just to a negligible degree.