PASCO ME-6814 User Manual

Includes

Teacher's Notes

and

Typical

Experiment Results

Instruction Manual and
Experiment Guide for

012-06293A

10/96

the PASCO scientific
Model ME-6814

MINI CATCHER ACCESSORY

MINI CATCHER

ME-6815

ACCESSORY

© 1996 PASCO scientific $10.00

012-06293A Mini Catcher Accessory

T able of Contents

Section Page

Copyright, Warranty, and Equipment Return ......................................................i i

Introduction .......................................................................................................1

Equipment.........................................................................................................1

Ball Catcher Setup.............................................................................................2

Velcro Assembly...............................................................................................2

Experiment 1: Ballistic Pendulum......................................................................3

Teacher’s Guide ...........................................................................................9

Technical Support ................................................................................... Back Cover

i

Mini Catcher Accessory 012-06293A

Copyright, Warranty and Equipment Return

Please—Feel free to duplicate this manual
subject to the copyright restrictions below.

Copyright Notice

The PASCO scientific 012-06293A manual is copy­righted and all rights reserved. However, permission
is granted to non-profit educational institutions for
reproduction of any part of the Mini Catcher Acces­sory manual providing the reproductions are used
only for their laboratories and are not sold for profit.
Reproduction under any other circumstances, without
the written consent of PASCO scientific, is prohibited.

Limited Warranty

PASCO scientific warrants the product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workman­ship. The warranty does not cover damage to the
product caused by abuse or improper use. Determina­tion of whether a product failure is the result of a
manufacturing defect or improper use by the customer
shall be made solely by PASCO scientific. Responsi­bility for the return of equipment for warranty repair
belongs to the customer. Equipment must be properly
packed to prevent damage and shipped postage or
freight prepaid. (Damage caused by improper packing
of the equipment for return shipment will not be
covered by the warranty.) Shipping costs for returning
the equipment, after repair, will be paid by PASCO
scientific.

Equipment Return

Should the product have to be returned to PASCO
scientific for any reason, notify PASCO scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and
shipping instructions will be promptly issued.

ä

NOTE: NO EQUIPMENT WILL BE

ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION FROM PASCO.

When returning equipment for repair, the units
must be packed properly. Carriers will not accept
responsibility for damage caused by improper
packing. To be certain the unit will not be
damaged in shipment, observe the following rules:

➀ The packing carton must be strong enough for the

item shipped.

➁ Make certain there are at least two inches of

packing material between any point on the
apparatus and the inside walls of the carton.

➂ Make certain that the packing material cannot shift

in the box or become compressed, allowing the
instrument come in contact with the packing
carton.

Address: PASCO scientific

10101 Foothills Blvd.
Roseville, CA 95747-7100

Phone: [phone]
FAX: [phone]
email: [e-mail]
web: www.pasco.com

ii

012-06293A Mini Catcher Accessory

Introduction

The PASCO ME-6814 Mini Catcher Accessory is used
with the PASCO ME-6825 Mini Launcher to perform
ballistic pendulum experiments. The Mini Catcher
functions as a ball catcher-pendulum. Students can
determine the initial velocity of the projectile, the height

Equipment

The Mini Catcher Accessory includes the following:

• a ball catcher

• support plate from which to hang the catcher

• spool of thread

• Velcro

• (2) chromed steel balls

®

assembly

achieved by the pendulum after ballistic collision with
the steel ball fired from the Mini Launcher, and the
percent loss of kinetic energy as a result of the elastic
collision.

The Mini Catcher Accessory is intended for use in a
supervised classroom setting.

support plate

rod clamp

ball catcher

MINI CATCHER

ME-6815

ACCESSORY

thread

1

Mini Catcher Accessory 012-06293A

Ball Catcher Setup

Suspending the Mini Catcher as a
Pendulum

Secure the rod clamp on top of the support plate to a
support rod that is clamped to the table. Cut two pieces
of string, each about one and a half meters long. Thread
one string through the front two holes in the ball catcher.
Thread the other through the back two holes in the ball
catcher. Thread the ends of the strings through the holes
in the support plate and secure them, making sure the
catcher hangs level. (See Figure 2.)

rod clamp

support rod

support plate

thread

Velcro Assembly

To enable the user to measure the height to which the
pendulum swings, a thread must be connected between
the ball catcher and the launcher. The amount of exten­sion of the string shows how far the pendulum swung.
One end of the string slips through a Velcro assembly on
the Mini Launcher base, and the other end threads
through a hole in the ball catcher. (See Figure 3.)

➀ Separate the Velcro hook and loop strips.
➁ Cut two square pieces of Velcro hook and one square

piece of Velcro loop.

➂ Determine the approximate height at which the Velcro

assembly will be applied. This is determined by the
approximate height of which the ball catcher hangs.

➃ Remove the protective covering from the back of each

Velcro square.

➄ Arrange the two square pieces of Velcro hook and one

square piece of Velcro loop onto the vertical plate of
the Mini Launcher base as shown (Figure 3).

➅ Cut one piece of Velcro loop 5 – 6 cm long. Do not

remove the protective backing.

support plate

string

MINI CATCHER

ACCESSORY

ME-6815

thumbscrew

ball catcher

➆ Tie a thread to one of the front holes in the ball

catcher as shown (Figure 3).

➇ The other end of this thread will pass between the

square piece of Velcro loop (attached to the Mini
Launcher base) and the long piece of Velcro loop
which should be applied to the three Velcro squares
attached to the Mini Launcher base.

Mini Launcher Base

Mini Launcher

Velcro

thread

Velcro loop

hook

Mini

Catcher

Figure 2. Suspending the Ball Catcher

Figure 3. Velcro Assembly

2

012-06293A Mini Catcher Accessory

Experiment 1: Ballistic Pendulum

EQUIPMENT NEEDED

– Mini Launcher and steel balls (ME-6825) – table clamp
– Mini Catcher Accessory (ME-6814) – meter stick
– Universal Table Clamp (ME-9376B) – white paper, carbon paper

– Support Rod (90 cm) (ME-8738) – plumb bob
– Right Angle Clamp (SE-9444) – mass balance

optional: Photogates and Photogate Bracket

Purpose

Students will determine the percent loss of kinetic energy as a result of an elastic collision by
determining the initial and final velocities of the projectile from the Mini Launcher and by using
the laws of Conservation of Energy and Conservation of Momentum.

Theory

A ball is launched horizontally and embeds in
the bob of a pendulum. The pendulum then
swings up to a particular height, h. (See Figure

1.1.)

Momentum is conserved during the collision, but

MINI CATCHER

ACCESSORY

ME-6814

kinetic energy is not. The momentum after the
collision is equal to the momentum before the

collision:

(1)

mbvo= mb+ mcv

Figure 1.1. Conservation of Energy

where mb is the mass of the ball, vo is the muzzle velocity of the ball, mc is the mass of the
catcher, and v is the velocity of the catcher (and ball) after the collision. (See Figure 1.2.)

Before Collision

Launcher

9

8

7

6

5

WEAR
SAFETY
GLASSES
WHEN IN USE.

DON’T PUSH

PISTON

WITH

FINGER!

CAUTION

4

4

3

3

2

2

1

1

0

ME-6825

MINI LAUNCHER

v

o

m

B

MINI CATCHER

ACCESSORY

ME-6814

m

C

Launcher

9

8

7

6

5

4

3

WEAR

2

SAFETY
GLASSES
WHEN IN USE.

DON’T PUSH

2

1

1

0

v

After Collision

PISTON

WITH

FINGER!

CAUTION

4

3

ME-6825

MINI LAUNCHER

MINI CATCHER

ACCESSORY

ME-6814

ME-6814

MINI CATCHER

ACCESSORY

mB + m

v = 0

h

v

C

Figure 1.2. Conservation of Momentum

3

Mini Catcher Accessory 012-06293A

y

x

t

x

t

The kinetic energy of the catcher (and ball) after the collision is converted completely to potential
energy at the top of the swing:

1

(2)

mb+ mcv2= mb+ mcgh

2

So to find the muzzle velocity of the ball, we begin with the potential energy of the pendulum at the
top of its swing and work backwards from there. From our equation for energy conservation (2):

v =2gh

(3)

Substitute (3) into the equation for momentum conservation (1):

mbv0= mb+ mc2gh

m

+ m

b

v0=

c

m

2gh

b

For comparison, the initial speed (muzzle velocity) of the ball is determined by shooting the ball
horizontally off the table onto the floor and measuring the vertical and horizontal distances through
which the ball travels.

Setup

➀

For a ball shot horizontally off a table with an initial speed, v
the ball is given by , where t is the time the ball is in the air. Air friction is assumed to be

= v

0

the horizontal distance (x) travelled by

0,

negligible.

2

1

The vertical distance (y) the ball drops in time t is given by .

y=

gt

2

The initial velocity of the ball can be determined by measuring x and y. The time of flight of the ball
can be found using

2

t =

and then the muzzle velocity can be found using .

g

vo=

Part I: Determining the Initial Velocity of the Ball

Clamp the Mini Launcher to a sturdy table near one end of the table. ( See Figure 1.3).

Mini Launcher

steel ball in flight

table

9

DON’T

8

PUSH

PISTON

7

WITH

6

5

CAUTION

4

4

3

WEAR

3

2

2

SAFETY

1

1

0

GLASSES
WHEN IN

ME-6825

MINI LAUNCHER

y

x

Figure 1.3. Setup for Part I: Determining V0, method 1

4

012-06293A Mini Catcher Accessory

➁ Adjust the angle of the Mini Launcher to zero degrees so the ball will be shot off horizon-

tally, away from the table onto the floor.

Procedure

➀ Using the pushrod that came with the Mini Launcher, put the steel ball into the Mini Launcher

and cock it in the long range position (three clicks).

➤ Important! Never look down the barrel of the Mini Launcher. You can tell whether the

Mini Launcher is loaded by looking at the viewing window located on the top front of the
barrel. If the window is clear, the Mini Launcher is loaded. If in doubt, place your hand
over the muzzle and pull the trigger.

➁ Fire one shot to locate where the ball hits the floor. At this position, tape a piece of white paper

to the floor. Place a piece of carbon paper (carbon-side down) on top of this paper and tape it
down. When the ball hits the floor, it will leave a mark on the white paper.

➂ Fire about ten more shots.
➃ Using a plumb bob as an aid, measure the vertical distance from the bottom of the ball as it

leaves the barrel (this position is marked on the side of the barrel) to the floor. Record this
distance in Table 1.1.

Find the point on the floor that is directly beneath the release point on the barrel. Measure the
horizontal distance along the floor from the release point to the leading edge of the paper.
Record in Table 1.1.

Measure from the leading edge of the paper to each of the ten dots and record these distances in
Table 1.1.

➄ Find the average of the ten distances and record in Table 1.1.
➅ Using the vertical distance and the average horizontal distance, calculate the time of flight and

the initial velocity of the ball.

➆ Record your data in Table 1.1 and Table

1.4.

Table 1.1 Determining the Initial Velocity

Vertical distance (y) = ______________.

Horizontal distance to paper edge = ____________.

Initial velocity (v

)= _______________.

0

5

Mini Catcher Accessory 012-06293A

Alternate Method: Determining the Muzzle Velocity with Photogates

➀ Attach the Photogate Bracket to the launcher and attach two Photogates to the bracket. Plug the

Photogates into a computer or other timer.

➁ Put the ball into the Mini Launcher and cock it to the long range position.
➂ Run the timing program and set it to measure the time between the ball blocking the two

Photogates.
Shoot the ball three times and take the average of these times.
Record in Table 1.2.
Use a distance between the Photogates of 10 cm, to calculate the initial speed and record it in

Table 1.2 and Table 1.4.

Table 1.2 Initial Speed Using Photogates

Trial Number

Average Time

Initial Speed

Part II: Ballistic Pendulum

Setup

➀ Find the masses of the ball and the catcher and

record in Table 1.3.

➁ Suspend the ball catcher as a pendulum as

explained in the general instructions.

➂ With the Mini Launcher mounted as in Figure

1.4, clamp the suspended ball catcher directly in
front of the muzzle.

Time

1
2
3

rod clamp

horizontal rod

90 cm steel rod

➃ Attach a thread to the ball catcher and string it

through the Velcro assembly (see the general
instructions) on the base of the Mini Launcher.

Procedure

➀ Load the Mini Launcher with the steel ball on

the long range setting. Fire a test shot to see how
far out the thread is pulled. Pull a few centime­ters of the thread back through the Velcro,
leaving the rest of the thread slack between the
Mini Launcher and the catcher. When the ball is
shot into the pendulum again the thread will

Mini Launcher

9

DON’T PUSH

8

PISTON

WITH

7

FINGER!

6

5

CAUTION

4

4

3

WEAR

3

2

2

SAFETY

1

1

0

GLASSES
WHEN IN USE.

ME-6825

Mini Launcher

base

clamp

Figure 1.4. Setup for Part II

6

MINI LAUNCHER

MINI CATCHER

ACCESSORY

ME-6814

Mini Catcher

table clamp

012-06293A Mini Catcher Accessory

E

E

become taut just before the catcher reaches its maximum height. This reduces the effect of
friction on the thread.

➁ Anchor the string on the Mini Catcher base with a piece of tape and measure the perpendicular

distance from the bottom of the Mini Catcher to the table.

➂ Fire the ball into the pendulum five times. After each trial, pull the pendulum back until the

thread is taut and measure the height above the level of the muzzle to which the pendulum
swung. Record in Table 1.3.

Analysis

➀ Calculate the average of the heights in Table 1.3 and record the result in Table 1.4. Using the

average height, calculate the velocity immediately after the collision and record it in Table 1.4.

➁ Using the velocity calculated in the previous step and the masses, calculate the muzzle velocity

of the ball and record in Table 1.4.

➂ Calculate the percent difference between the muzzle velocities found in Parts I and II. Record in

Table 1.4.

Table 1.3 Ballistic

Pendulum Data

Table 1.4 Results

Mass of Ball = _____________.
Mass of Catcher = __________.

Average Height

Height

v0, Method 1 (Part I)

v0, Method 2 (Part II)

v (ball + catcher)

KE before collision

KE after collision

% difference in KE

Questions:

➀ What percentage of the kinetic energy is lost in the collision? Use the masses and velocities to

calculate this percentage:

% Lost =

K

before

KE

- K

before

after

x 100%

➁ Where did the kinetic energy go?

7

Mini Catcher Accessory 012-06293A

Notes

8

012-06293A Mini Catcher Accessory

Teacher’s Guide

Experiment 1

Hints for successful data collection (Part II):

• Be sure that the Mini Catcher is level and hanging close to, but not touching, the
Mini Launcher.

• Check to be sure the muzzle is aligned with the foam pad.

• Be sure the string moves freely in the Velcro assembly.

• Check to be sure the support plate is perpendicular to the table.

• To be sure any force exerted by the string attached to the Mini Catcher is mini­mized, leave enough slack in the string to necessitate its being pulled only a few
centimeters at the top of the swing of the Mini Catcher.

• Be sure to tape the string to the Mini Launcher base after firing the Mini Launcher
and before measuring h.

• Be sure students are using for their velocity calculations in Part II the ∆h of the
bottom of the Mini Catcher, not the absolute height above the table top of the
bottom of the Mini Catcher.

A Sample Data Set:

mass of steel ball = .016 kg
mass of Mini Catcher = .024 kg
ave. ∆h = 0.16 m
y = 0.77 m
x = 1.8 m

v

(Part I) = 4.5 m/s

0

v

(Part II) = 4.4 m/s

0

K.E. before collision = 0.15 Joule
K.E. after collision = 0.063 Joule
Loss of K.E. = 58 %

Question 2:

The remainder of the K.E. was converted primarily to heat energy that was dissipated in
the foam pad. Other potential contributors to kinetic energy loss include torque in the
swing path of the Mini Catcher and potential energy in the elastic deformation of the
foam pad by the steel ball.

9

Mini Catcher Accessory 012-06293A

Notes

10

T echnical Support

Feedback

If you have any comments about the product or
manual, please let us know. If you have any sugges­tions on alternate experiments or find a problem in the
manual, please tell us. PASCO appreciates any
customer feedback. Your input helps us evaluate and
improve our product.

To Reach PASCO

For technical support, call us at 1-800-772-8700 (toll­free within the U.S.) or [phone].

fax: [phone]
e-mail: [e-mail]
web: www.pasco.com

Contacting Technical Support

Before you call the PASCO Technical Support staff, it
would be helpful to prepare the following informa­tion:

➤ If your problem is computer/software related, note:

 Title and revision date of software;
 Type of computer (make, model, speed);
 Type of external cables/peripherals.

➤ If your problem is with the PASCO apparatus, note:

 Title and model number (usually listed on the

label);

 Approximate age of apparatus;
 A detailed description of the problem/sequence

of events. (In case you can’t call PASCO right
away, you won’t lose valuable data.);

 If possible, have the apparatus within reach when

calling to facilitate description of individual parts.

➤ If your problem relates to the instruction manual,

note:

 Part number and revision (listed by month and

year on the front cover);

 Have the manual at hand to discuss your ques-

tions.