Ballistic Pendulum and Projectile Motion
Ballistic Pendulum and Projectile Motion
lab6
10/20/2020
Kean University
Your name here
Purpose
With ballistic pendulum experiment, get a better understanding how to apply momentum conservation and energy conservation in specific cases. Understand and calculate how a vector based projectile motion could be treated as two one-dimension scalar motions.
Part I -- Ballistic Pendulum
Theory
Assuming a bullet with a mass is fired horizontally with a height referenced to the surface of a table, with an initial speed of , hits a still pendulum with a mass of and the bullet is within the pendulum. Then the pendulum oscillates and reaches a maximum height of meter.
For analysis reason, the whole process can be separated into two parts: firstly it is the bulletin and pendulum collision, which follows the momentum conservation law (one dimension case, see equation (1)) supposing the after collision speed is ; secondly, the pendulum plus the bullet system sways from to , and keep going on back and forth, which follows the total energy conservation law (see equation (2)).
XXXXXXXXXX1)
XXXXXXXXXXenergy conservation, we have XXXXXXXXXX)
If we solve for the initial speed , we get
XXXXXXXXXX3)
where h is the maximum height change,
Note: if g=9.8 m/s2, then h must be in meters.
Virtual La
Site: https:
ophysics.com/e3.html
Lab procedure:
1)record bullet mass--, wood box mass--, initial speed (check the box)
2) move the dot on the vertical bar (right side on the left figure), record your
3) click “fire”.
3) click “pause” when the wood box is at the highest point (try your best). Then measure your
Data Recording
XXXXXXXXXXTable1 -- Data Table
(kg)
(kg)
(m/s)
(m)
(m)
h (m)
Analysis
Calculate the bullet initial speed using equation (3) above, your
Calculate the percent e
or with the initial from table 1 and your calculated using equation (3).
Part II---Projectile Motion
Theory
For a projectile motion like the figure displays, if the bullet flying time is t, horizontal distance is x and vertical is y,
Then we can treat the vertical direction as a free fall with a zero-initial speed, and horizontal direction as a constant speed motion with a speed of .
We have
XXXXXXXXXX5)
If we solve for , we can get
XXXXXXXXXX6)
Virtual La
Site: https:
phet.colorado.edu/sims/html/projectile-motion/latest/projectile-motion_en.html
Procedure:
Raise the shooting platform to 10 meters height, then bend the shooting pipe to zero degree, by adjusting the speed and shooting angle, try your best to let the bullet falls close to 15 meters target as close as possible. Then record the height and your initial speed, also measure the exact location (
ing the measuring meter to the spot) where your bullet landed.
Data Recording
Table2 – Data table
Angle (degree)
Height y (meters)
Initial speed (m/s)
Location landed x (meters)
0
10
Analysis
Plug x and y values from table2 into equation (6) to calculate the initial speed
Do percent e
or calculation (initial speed in table2 as the true value) comparing your calculated speed and initial speed in table2.
Conclusion/Discussion
What have your learned from these two experiments? What about the percent e
ors?