Ballistic Pendulum.

“Ballistic pendulum; It is used to determine the speed of exit of the bullet from the weapon”.

Groups:

Group 01	Aslı Asuman, Burcu Erdem, Eray Beyaz
Group 02	Olcay Haser, Emirhan Çubukçu
Group 03	Semih Aydemir, Sinan Uğural
Group 04	Esma Yazıcı, Fatma Aleyna Gürel
Group 05	Asiye Aksu, Arif Kalaycı

While the measurements were made, it was tried to use the method that made the most practical measurement.

Date of measure 15:00-26.12.2019

Estimates:

Group	18 g marble v (m/s)	53 g marble v (m/s)
Group 01	3,2	2,0
Group 02	3,5	2,5
Group 03	3,8	2,4
Group 04	4,0	3,0
Group 05	2,5	1,8

Tools:

Horizontal firing device, balls (wrapped around adhesive fabric), pendulum-chock wrapped around adhesive fabric, angle meter, smart phone (for video and photo shooting), ruler, scales, metal support and clamps.

Description of measurement method:

Horizontal shot and ballistic pendulum assembly is installed.
The balls to be launched and the pendulum-wedge are covered with adhesive fabric.
The masses of the pendulum wedges and balls are measured.
The angle gauge is adjusted according to the pendulum.
Shot distance is pendulum close to the trigger is pressed.
It is determined how many degrees and how many meters the adhering ball and pendulum system together.
Using the momentum and energy conservation laws, the shot velocity of the ball is calculated.
The measurements are repeated for balls of different mass.

Theoretical information:

Ballistic pendulum

Ballistic pendulum task

Using formula for calculating:

From conservation of momentum;

From conservation of energy;

İnitial speed from these equations;

: bullet mass

: pendulum mass

: speed of common mass

initial speed of bullet

Height amount of pendulum

Data Gruop 4:

Marble mass (kg)	Pendulum-wedge mass (kg)	Gravitation acceleration (m/s2)	Elevation angle (degree)	Height amount (m)	İnitial speed of marble (m/s)
0,014	0,130	9,81	18	0,007	2,96
0,018	0,130	9,81	20	0,008	3,26
0,053	0,130	9,81	43	0,034	2,36

Note: Marble shot was made at a distance of 8 cm pendulum.

İnitial speed- vertical displacement graph:

Graphic: it is a graph of V=K.(h)½ . Where K is constant that contains (m,M,g), and h is the raising amount of pendulum, and V is the velocity of ball (marble) hitting the pendulum. Horizontal axis is h, vertical axis is V. Right side is important for real motion.

Experiment photo:

Our measurements:

Group	m (kg)	M(kg)	g (m/s2)	(degree	h (m)	v (m/s)
Group 01	0,014	0,130	9,81	18	0,006	2,74
Group 02	0,014	0,130	9,81	19	0,007	2,96
Group 03	0,014	0,130	9,81	21	0,008	3,17
Group 04	0,014	0,130	9,81	18	0,007	2,96
Group 05	0,014	0,130	9,81	20	0,008	3,17

Group	m (kg)	M(kg)	g (m/s2)	(degree	h (m)	v (m/s)
Group 01	0,018	0,130	9,81	21	0,008	3,26
Group 02	0,018	0,130	9,81	20	0,008	3,26
Group 03	0,018	0,130	9,81	21	0,008	3,26
Group 04	0,018	0,130	9,81	20	0,008	3,26
Group 05	0,018	0,130	9,81	23	0,009	3,46

Group	m (kg)	M(kg)	g (m/s2)	(degree	h (m)	v (m/s)
Group 01	0,053	0,130	9,81	45	0,035	2,86
Group 02	0,053	0,130	9,81	40	0,028	2,14
Group 03	0,053	0,130	9,81	38	0,025	2,02
Group 04	0,053	0,130	9,81	43	0,034	2,36
Group 05	0,053	0,130	9,81	42	0,033	2,32

Average speed for 0,014 kg: v=3,00 m/s

Average speed for 0,018 kg: v=3,30 m/s

Average speed for 0,053 kg: v=3,34 m/s

Conclusion and discussion :

The speed of exit of a bullet from the gun can be measured by various methods. But, the most widely used technique is the ballistic pendulum technique.
The movement of the ballistic pendulum can be monitored in slow motion video.
Measurement errors due to friction. We have tried to minimize this in our measurement.
The horizontal firing device fires different mass balls at different speeds. This is due to the fact that the system is springy.

Mehmet Taşkan

Web: www.fizikevreni.com

e-mail: fizikevreni@mynet.com