PASCO ME-6800 Projectile Launcher (Short Range) - Manual (Page 15)

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M o d e l N o . M E - 6 8 0 0 E x p . 2 : P r o j e c t i l e M o t i o n U s i n g P h o t o g a t e s
0 1 2 - 0 5 0 4 3 G 11
Exp. 2: Projectile Motion Using Photogates
Equipment Needed
*See the PASCO web site at www.pasco.com for information about PASCO interfaces, timers, and data acquisition software.
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 speed of the ball.
Theory
To predict where a ball will land on the floor when it is shot from the Launcher at some angle above the horizontal,
it is first necessary to determine the initial speed (muzzle velocity) of the ball. The speed can be determined by
shooting the ball and measuring a time using photogates. To predict the range, x, of the ball when it is shot with an
initial speed at an angle,
, above the horizontal, first predict the time of flight using the equation for the vertical
motion:
where y
0
is the initial height of the ball and y is the position of the ball when it hits the floor. Solve the quadratic
equation to find the time, t. Use x = (v
0
cos
 t to predict the range.
Setup
1. Clamp the Projectile Launcher to a sturdy table or other horizontal surface. Mount the Launcher near one end
of the table.
2. Adjust the angle of the Projectile Launcher to an angle between 30 and 60 degrees and record the angle.
3. Attach the photogate mounting bracket to the Launcher and attach two photogates to the bracket. Check that
the distance between the photogates is 0.10 m (10 cm).
4. Plug the photogates into an interface or a timer.
Procedure
Part A: Determining the Initial Speed of the Ball
1. Put a plastic ball in the Projectile Launcher and use the ramrod to cock it at the long range position.
2. Setup the data acquisition software or the timer to measure the time between the ball blocking the two photo-
gates.
3. Shoot the ball three times and calculate the average of these times. Record the data in the Data Table.
4. Calculate the initial speed of the ball based on the 0.10 m distance between the photogates. Record the value.
Item Item
Projectile Launcher and plastic ball Plumb bob and string
Photogate Head ME-9498A (2) Photogate Mounting Bracket ME-6821A
PASCO Interface or Timer* PASCO Data acquisition software*
Meter stick Carbon paper
White paper Sticky tape
y y
0
v
0

sin
 t 1
2
---gt
2
– + =