Pasco Scientific ME-6825, Инструкция по эксплуатации и руководство по экспериментам

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012-05479A Mini Launcher
7
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 launch-
ing 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.
INITIAL HORIZONTAL VELOCITY:
For a ball launched horizontally off a table with an initial speed, v
o
, the horizontal distance trav-
elled by the ball is given by x = v
o
t , 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
y = 1
2
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:
t =
2 y
g
and then the initial velocity can be found using
v
0
=
x
t
.
INITIAL VELOCITY AT AN ANGLE:
To predict the range, x, of a ball launched with an initial velocity at an angle,
θ
, above the horizon-
tal, first predict the time of flight using the equation for the vertical motion:
y = y
0
+ v
0
sin
θ
t – 1
2
gt
2
where y
o
is the initial height of the ball and y is the position of the ball when it hits the floor. Then
use
x = v
0
cos θ t
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.
90
80
70
60
50
40 30 20 10
0
10
20
30
40
MINI LAUNCHER
ME-6825
CA
U
T
I O
N
!
W
EA
R
S
AFE
TY
G
L
A SS
E S
WH
E N
I
N
U S
E
.
D
O
N '
T
PU
S
H
P
I S
T
O N
W
I
T H
F I
N GE
R !
Figure 1.1: Setup to shoot
horizontally off table