PASCO ME-6825A MINI LAUNCHER - Manual (Page 13)

012-05479B Mini Launcher
11
®
Experiment 2: Projecile Motion Using Photogates
EQUIPMENT NEEDED
– Mini Launcher and steel ball – Photogate bracket
– (2) Photogates – Computer and Timing software
– Plumb bob – Meter stick
– Carbon paper – White paper
Purpose
The purpose of this experiment is to predict and verify the range of a ball launched at an angle.
Photogates are used to determine the initial velocity of the ball.
Theory
To predict where a ball will land on the floor when it is shot off a table at an angle, it is necessary to first
determine the initial speed (muzzle velocity) of the ball. This can be determined by shooting the ball and
measuring the speed using photogates. To predict the range, x, of the ball when it is launched with an
initial velocity at an angle
θ, above the horizontal, first predict the time of flight using the equation for
the vertical motion:
y = y
0
+ v
0
sin q t - 12 gt 2
where y
o
is the initial height of the ball and y is the position of the ball when it hits the floor. Then
use x = v
0
cos
θ
t to find the range. If the ball is shot at an angle below the horizontal,
θ is nega-
tive.
Setup
➀
Clamp the Mini Launcher near one end of a sturdy table as shown in Figure 2.1.
➁
Adjust the Mini Launcher to launch either at an angle between 20 and 60 degrees above the horizontal,
or 10 to 40 degrees below.
➂
Attach the photogate bracket to the Launcher and attach two photogates to the bracket. Plug the
photogates into a computer or other timer.
Figure 2.1: Setup to determine
initial velocity