Experiment : Trajectory LAB

Daniel Jung
Eddie Park, Peter Han
Physics/ 2
Mr. Elwer
Procedure
    1. Prepare materials : balls , cones for measurement, a tape measure, angle measurers.
    2. Go to an even field.
    3. Stand in an appropriate place to throw and set an approximate point for the ball to fall.
    4. Find the midpoint between the throwing point and falling point.
    5. Another person have to stand on the midpoint. Step back perpendicularly so that the person can measure the angle of the ball in the air.
    6. Throw the ball.
    7. The second person will measure the angle of the ball at the highest point by using the angle measurer.
    8. The other person will set the cone at the point at which the ball's dropped at.
   
    9.  Measure the distance between the starting point and the dropped point.
   10. Calculate the initial velocity of the ball.



















< The ball's thrown by x degree from the horizontal line>

Data&Analysis

Trials	1st	2nd
Distance	15.9m	15.0m
	15.45m
Angle	52⁰	60⁰
Average Height	12m

    1. The highest height can be measured by trigonometric method. We can get the averaged length by calculating (2.0+7.0tan52+2.0+7.0tan60)/2 = 12.
    2. Using the background knowledge that the ball's vertical velocity is zero at its highest point, we can come up with this equation. -12 indicates the height.

h = h_i + v_it + at²/2= (-12) = 2+ 0 + (-9.81)t²/2

t= 1.689 = 1.7s (the time for the ball to reach its highest point)

Then, we can figure out the initial, vertical velocity (v_y).

0 = v_y + at = v_y + (-9.81)(1.689)
Thus,
v_y = 16.5735 = 17 m/s

As the horizontal velocity is constant,

v_x = 15.45/1.689 = 9.14742 = 9.1 m/s

Using pitagorian theorem,

vi = (9.1² + 17² )^1/2= 19 m/s

Degree x= arctan((12-2)/7.725) = 54 degrees