# Physical Science Lab Exercise - DOC

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```					                                    Physical Science Lab Exercise
Projectile Motion
Name_____________________________________________________________________________________

Lab Partner(s) ______________________________________________________________________________

Date______________________________________________________________________________________

Lab Station Number_________________________________________________________________________

Materials List:
Bent “track”    Marble(s)       Regular Paper Carbon Paper Masking Tape Scissors
Plumb Bob       Meter Stick     String        Projectile Launcher large Table Clamp

Objectives:
1) Draw and label the paths of an object undergoing projectile motion from low and high angles.
2) Describe specifically how to calculate the range of a bullet shot horizontally above the ground.
3) Identify the theoretical initial angle necessary to produce the maximum range possible for an object
undergoing projectile motion. Discuss the symmetry of ranges on both sides of this angle.
4) Apply projectile motion outside of the lab to a real life experience.

Description of Concepts:

Imagine taking practice at a shooting range. When a gun is fired level with the
horizon, the bullet will come out of the gun and eventually hit it’s target. But what if it
missed the target and continued on it’s path? When would it hit the ground? How far
would the bullet go before it hit the ground?
Here is a very specific example with information provided by a local gun shop. A
typical 9mm gun can shoot out a bullet with a muzzle velocity of 350 meters/second. A
person standing with this gun 1.5 meters above the ground fires it level. When will this
bullet reach the ground?
For free fall, to calculate the vertical distance time for an object to hit the ground:
1
Y = gt 2,
2Y  t 2,t       2Y
2        g                  g

t=
21.50m  0.553seconds
m
9.8
                              s2

13

To find the range, take the vertical time and put it into the familiar Distance = Velocity
* Time (This time the distance is horizontal)
m
X = V * t = 350 * 0. 553seconds   193meters
s
Procedure:
Part I:
Clamp the bent metal track to the end of a table. Measure the height (Y) of where
the marble will fall from the end of the track. Put a plumb bob directly under where the
ball will fall from the end of the track. Put the marble at the top of the track and let it
go. Find the approximate place where it lands and put a piece of paper there. Repeat to
make sure the paper is in the right place. Tape the paper to the floor. Place a piece of
carbon paper (dark side down) on top of the taped paper, but do not tape the carbon
paper; leave it loose. Roll the marble down the track five times allowing it to hit the
carbon paper. Make sure to prevent the marble from rebounding off anything to come
back to the carbon and leave a stray mark. Remove the carbon paper and measure the
distance from where the plumb bob is just above the floor to each mark produced on the
paper. If some of the marks overlapped, that is OK. Record this distance in meters as
the range (X) of the marble projectile. Using the previous example, calculate the time of
the marble projectile during its flight. Since the horizontal velocity of the marble
projectile is not known, but the range is measured, the horizontal velocity can be
calculated by using the Distance Formula: X = V*t. Use the average horizontal
distance and divide it by the calculated time to get the horizontal velocity.
Repeat the experiment with the larger marble. (5 times, measure the distances, and
calculate the average distance and horizontal velocity)
PartII:
With the projectile launcher set out in the hallway, shoot the ball at different
angles with respect to the floor. Use the SHORT RANGE, (one click). Be careful not to
hit the rock cabinets. Vary the angle from horizontal (0°) to 75° in 5 degree incremental
steps. Use the tape measure and record the range of the projectile launcher for each 5
degree increment. See if the maximum range angle can be determined by the ranges
measured. Each lab station will do two of the angles. Record the ranges on the
chalkboard to share.
Angle Range         Angle Range         Angle Range        Angle Range

0°    _______      5°     _______      10°    _______      15°   _______

20°   _______      25°    _______      30°    _______      35°   _______

40°   _______      45°    _______      50°    _______      55°   _______

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60°    _______         65°    _______         70°    _______         75°    _______

Analysis and lab notes: The accompanying excel sheet will do all the necessary calculations, but you
are required to input the correct data in the correct locations. The data includes the vertical height and
the ten trials (two sets of five) of the horizontal range of the two different marbles. The main results
include the average time it took the two marbles to reach the floor and the two average horizontal
velocities. You should also make a conclusion about the maximum range (and the associated angle)
for the projectile launched out in the hallway. List potential sources of error. All 5 of the essential
components of the lab report should be included! Make sure to attach the excel sheet to the lab report.
Use the separate tables on the second excel sheet (copy and paste) to list the data and results in the lab
report. It is recommended that you highlight the tables and copy them using the “paste special” as a
excel object in the lab report.

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