PASCO ME-6825A User Manual

Instruction Manual and Experiment Guide for the PASCO scientific Model ME-6825A

MINI LAUNCHER

012-09562A

7 0

Third C

Long Range

lick

CAUTION!

Second Click

edium

Range

DO NOT LOOK DOWN BARREL.

E-6825A

First Click

Short R

ange

Push with Pen or Rod

Until Piston Clicks

MINI LAUNCHER

l b

lls

Launch

Position

of Ball

012-09562A Mini Launcher

Table of Contents

Section Page

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

Equipment .........................................................................................................2

General Operation Of The Mini Launcher .......................................................... 3

Installation Of The Optional Photogate Bracket .................................................. 4

Installing the 2-Dimensional Collision Attachment .............................................. 5

Expectations For The Mini Launcher ................................................................. 5

Launch Positions ............................................................................................... 6

Experiments

1. Projectile Motion ....................................................................................7

2. Projectile Motion Using Photogates ....................................................... 11

3. Projectile Range versus Angle ............................................................... 15

4. Projectile Path ....................................................................................... 19

5. Conservation of Energy ........................................................................ 23

6. Conservation of Momentum in Two Dimensions ................................... 27

7. Varying Angle to Maximize Height on a Wall ....................................... 31

8. Demo: Do 30° and 60° Give Same Range? ........................................... 33

9. Demo: Simultaneously Shoot Two Balls

Horizontally at Different Speeds .......................................................... 34

10. Demo: Shooting through Hoops ........................................................... 35

Technical Support ..................................................................................... back cover

012-09562A Mini Launcher

Introduction

The PASCO Mini Launcher has been designed for projectile experiments and demonstrations. The only additional equipment required is a C-clamp or ME-9376B Universal Table Clamp for clamping the Launcher to a table. The features of the Mini Launcher include:

• LAUNCH AT ANY ANGLE Between -45° and 90°:

Balls can be launched at any angle from 0 to 90 degrees measured above the horizontal. The magnetic piston holds the steel ball in position for launch at any angle from 0 to 45 degrees measured below the horizontal.

WEAR SAFETY GLASSES WHEN IN USE.

DO NOT PUSH

PISTON

WITH

FINGER!

The angle is easily adjusted using the thumb screw. The built-in protractor and plumb bob on the side of the launcher give a convenient and accurate way of determining the angle of inclination.

• THREE RANGE SETTINGS: There are three ranges from which to choose.

They are approximately 0.5 meter, 1.0 meter, and

2.0 meters, when the angle is 45 degrees and measured from table top to table top.

• FIXED ELEVATION INDEPENDENT OF ANGLE:

steel balls ONLY!

Pen or Rod

on Clicks

Launch

Position

of Ball

UNCHER

Ball

Center of mass

Outer edge

of Ball

The Mini Launcher can be mounted so that it pivots at the muzzle end. The elevation of the ball as it leaves the barrel does not change as the angle is varied.

• REPEATABLE RESULTS: There is no spin on the ball since the piston keeps

the ball from rubbing on the walls as it travels up the barrel. The sturdy base can be secured to a table with a C- clamp or a ME-9376B Universal Table Clamp (not included) so there is very little recoil. The trigger is pulled with a string to minimize jerking.

• COMPUTER COMPATIBLE: Photogates may be attached with the accessory

bracket (ME-6821A) to connect the Mini Launcher to a computer to measure the muzzle speed. Also a photogate at the muzzle and the Time of Flight accessory (ME-6810) can be used to time the flight of the ball.

Mini Launcher 012-09562A

Equipment

The ME-6825 Mini Launcher includes the following:

• Launcher and Base (Assembled)

• (2) 16mm Steel Balls

• String (to pull trigger)

• Collision Attachment

• Safety Goggles

• Pushrod

• Manual

Safety Goggles

Launcher

8 0

WEAR

SAFETY GLASSES

WHEN IN USE.

Angle Indicator

Trigger

Collision Attachment

DO NOT PUSH

PISTON

WITH

FINGER!

Third Click

Long Range

Second Click

Medium Range

CAUTION!

ME-6825A

First Click

Short Range

DO NOT LOOK DOWN BARREL.

MINI LAUNCHER

Use 16 mm steel balls ONLY!

Push with Pen or Rod

Until Piston Clicks

itio

f B

String

Pushrod

Projectile Balls

Base

012-09562A Mini Launcher

General Operation of the Mini Launcher

➀ Ready

- Always wear safety goggles when you are in a room where the Mini Launcher is being used.

CAUTION: Never look down the front of the barrel because it may be loaded. Safety goggles are provided for use when operating the Mini Launcher. Always assume that the barrel is loaded!

- Tie the string to the trigger before loading.

- The base of the Mini Launcher can be clamped to the edge of a table using the clamp of your choice. When shooting onto the floor, it is desirable to have the label side of the Launcher even with one edge of the table so a plumb bob can be used to locate the position of the muzzle with respect to the floor. See page 6 for mounting options.

- The Mini Launcher can be mounted to shoot onto the table such that the launch position of the ball is at the same height as the table.

NOTE: To prevent the steel ball from denting your floor or table top, you may want to place a protective plastic or metal covering on the surface.

➁ Aim

- Place the ball in the barrel. Push the ball down the barrel with the pushrod until the trigger catches the piston. One audible click indicates that the piston is cocked in the shortest range setting, two clicks indicate the medium range and three clicks set the piston on the long range setting.

Third Click

Long Range

Second Click

Medium Range

First Click

Short Range

- Remove the pushrod.

CAUTION: Do not push the piston with

your finger. Your knuckle may get stuck.

➃ Shoot

- Before launching the ball, make certain that no person is in the way.

- To shoot the ball, pull straight up on the string that is attached to the trigger. It is only necessary to pull it about a centimeter.

➄ Storage

- Store the Launcher with the spring uncompressed.

- The angle of inclination is adjusted by loosening the thumb screws and rotating the Launcher to the desired angle above or below the horizontal as indicated by the plumb bob and protractor on the side of the Launcher. When the angle has been selected, tighten the thumb screw.

- To help align the launcher with a target, use a straight edge or meter stick against the lip on the launcher barrel as illustrated.

➂ Load

- Always cock the launcher with the ball in the piston.

NOTE: Use only 16 mm steel balls with the

Mini Launcher.

TP '

R E

G N

0 4

9 0

0 3

0 2

7 0

0 1

6 0

0 1

4 0

0 2

3 0

N A L

E H W

Aligning launcher and

target with meter stick

Mini Launcher 012-09562A

Installing the Optional Photogate Bracket (ME-6821)

The Photogate Bracket is an optional accessory for mounting one or two photogates on the Mini Launcher to measure the muzzle velocity of the ball.

Installation is as follows: ➀ Prepare the bracket by inserting the thumb screw

through the hole in the bracket near the end and start the square nut onto the end of the thumb screw (see diagram).

Attach the photogates to the bracket using the remaining holes in the bracket and the screws pro-

Mini

Launcher

Barrel

vided with the photogates.

➁ To mount the bracket to the Launcher, align the

square nut in the slot on the bottom of the Launcher and slide the nut into the slot. Slide the bracket back until the photogate nearest to the barrel is as close to the barrel as possible without blocking the beam. Tighten the thumb screw to secure the bracket in place.

➂ When storing the Mini Launcher, the photogate

bracket need not be removed. It can be slid back along the barrel with or without the photogates in place, making as compact a package as possible.

Square

Nut

Photogate Mounting

Bracket

Photogate

Thumb Screw

Nylon Thumb

Screw

Nylon Thumb

Screw

012-09562A Mini Launcher

Installing the 2-Dimensional Collision Attachment

The two dimensional Collision Attachment consists of 2 screws, 2 nuts, and a flat plastic bar. It is used with the Mini Launcher to hold a second ball in front of the muzzle so the launched ball will collide with the second ball, creating a 2-dimensional collision.

Assembly

To assemble the collision attachment , insert the screws through the holes and secure with the nuts as shown in the following illustration.

To mount the collision attachment to the Launcher the square nut slides into the T-shaped channel on the bottom of the Launcher. (See Experiment Figure 6.2)

Expectations for the Mini Launcher

Square

Nut

Hex Nut

The following are helpful hints and approximate values you may find useful:

➀ The muzzle speed will vary slightly with angle.

The difference between muzzle speed when shot horizontally versus vertically can be anywhere from zero to 8%, depending on the range setting and the particular launcher.

➁ The scatter pattern is minimized when the Mini

Launcher base is securely clamped to a sturdy table. Any wobble in the table will show up in the data.

➂ The angle of inclination can be determined to

within one- half of a degree.

Mini Launcher 012-09562A

Launch Positions

Clamp base to table. Mount launcher as shown to shoot onto table. The square nut that the Launcher pivots around should be slid to the front of the launcher. Ball is launched at table level. When you change the angle of the launcher, the launch position does not change.

Clamp base to table. Mount launcher as shown to shoot onto table. Ball is launched from a height above table level.

Clamp base to side edge of table. Mount launcher as shown to shoot off table onto floor at a positive or negative angle.

Clamp base to a vertical rod.

Place base on a tabletop or floor and hold it with your hand.

012-05479B Mini Launcher

y=y

sin

1 2

v0=

Experiment 1: Projectile Motion

EQUIPMENT NEEDED:

– Mini Launcher and steel ball – Plumb bob – Meter stick – Carbon paper – White paper

Purpose

The purpose of this experiment is to predict and verify the range of a ball launched at an angle. The initial velocity of the ball is determined by shooting it horizontally and measuring the range and the height of the Launcher.

Theory

To predict where a ball will land on the floor when it is shot off a table at an angle, it is necessary to first determine the initial speed (muzzle velocity) of the ball. This can be determined by launching the ball horizontally off the table and measuring the vertical and horizontal distances through which the ball travels. Then the initial velocity can be used to calculate where the ball will land when the ball is shot at an angle.

Figure 1.1: Setup to shoot

horizontally off table

INITIAL HORIZONTAL VELOCITY:

For a ball launched horizontally off a table with an initial speed, vo, the horizontal distance travelled by the ball is given by x = vot, where t is the time the ball is in the air. Air friction is assumed to be negligible.

The vertical distance the ball drops in time t is given by

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:

t =

and then the initial velocity can be found using

INITIAL VELOCITY AT AN ANGLE:

To predict the range, x, of a ball launched with an initial velocity at an angle, θ, above the horizontal, first predict the time of flight using the equation for the vertical motion:

y=y

sin

where yo is the initial height of the ball and y is the position of the ball when it hits the floor. Then use

= v0cos

to find the range. If the ball is shot at an angle below the horizontal, then θ is negative.

Setup

➀ Clamp the Mini Launcher near one end of a sturdy table as shown in Figure 1.1.

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

Mini Launcher 012-05479B

Procedure

Part A: Determining the Initial Velocity of the Ball

➀ Put the ball into the Mini Launcher and cock it to the long range position. 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.

➁ Fire about ten shots.

➂ 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.

➃ Use a plumb bob to 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.

➄ Measure from the leading edge of the paper to each of the ten dots and record these

distances in Table 1.1.

➅ Find the average of the ten distances and record the value in Table 1.1.

➆ Using the vertical distance and the average horizontal distance, calculate the time of

flight and the initial velocity of the ball. Record in Table 1.1.

➇ Calculate the Total Average Distance. Record in Table 1.1.

Table 1.1 Determining the Initial Velocity

Vertical distance = _____________ Horizontal distance to paper edge = ____________ Calculated time of flight = _________ Initial velocity = _______________

Trial Number Distance

1 2 3 4 5 6 7 8 9

Average Distance

Total Average Distance

012-05479B Mini Launcher

(Total Average Distance = Distance to paper edge + Average Distance)

Part B: Predicting the Range of the Ball Shot at an Angle

➀ Adjust the Mini Launcher to launch at an angle between 20 and 60 degrees above the horizontal. Record

this angle in Table 1.2.

➁ Using the initial velocity and vertical distance found in the first part of this experiment, calculate the new

time of flight and the new horizontal range for a projectile launched at the new angle. Record in Table

1.2.

➂ Draw a line across the middle of a white piece of paper and tape the paper on the floor so the line is at

the predicted horizontal distance from the Mini Launcher. Cover the paper with carbon paper.

➃ Shoot the ball ten times.

➄ Measure the ten distances and take the average. Record in Table 1.2.

Analysis

➀ Calculate the Total Average Distance. Record in Table 1.2.

(Total Average Distance = Distance from Edge of Paper + Horizontal Distance to paper edge)

➁ Calculate and record the percent difference between the predicted value and the resulting average

distance when shot at an angle.

➂ Estimate the precision of the predicted range. How many of the final 10 shots landed within this range?

Table 1.2 Confirming the Predicted Range

Angle above horizontal = ______________ Horizontal distance to paper edge = ____________ Calculated time of flight = _____________ Predicted Range = ____________

Trial Number Distance from Edge of Paper

1 2 3 4 5 6 7 8 9

Average

Total Average Distance

Mini Launcher 012-05479B

Part C: Predicting the Range of the Ball Shot at a Negative Angle

➀ Adjust the Mini Launcher to launch at an angle between 10 and 40 degrees below the

horizontal and record this angle in Table 1.3.

➁ Using the initial velocity and vertical distance found in the first part of this experiment,

calculate the new time of flight and the new horizontal range for a projectile launched at the new angle. Record in Table 1.3.

➂ Draw a line across the middle of a white piece of paper and tape the paper on the floor so

the line is at the predicted horizontal distance from the Mini Launcher. Cover the paper with carbon paper.

➃ Shoot the ball ten times.

➄ Measure the ten distances and take the average. Record in Table 1.3.

Analysis

➀ Calculate the Total Average Distance. Record in Table 1.3.

(Total Average Distance = Distance from Edge of Paper + Horizontal Distance to paper edge)

➁ Calculate and record the percent difference between the predicted value and the resulting

average distance when shot at an angle.

➂ Estimate the precision of the predicted range. How many of the final 10 shots landed

within this range?

Table 1.3 Confirming the Predicted Range

Angle below horizontal = ______________ Horizontal distance to paper edge = ____________ Calculated time of flight = _____________ Predicted Range = ____________

Trial Number Distance from Edge of Paper

1 2 3 4 5 6 7 8 9

Average

Total Average Distance

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