PASCO ME-6825A MINI LAUNCHER - Manual (Page 9)

012-05479B 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 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.
INITIAL HORIZONTAL VELOCITY:
For a ball launched horizontally off a table with an initial speed, v
o
, the horizontal distance travelled 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 negli-
gible.
The vertical distance the ball drops in time t is given by
y= y
0
+ v
0
sinq t -
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 =
2y
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 horizontal,
first predict the time of flight using the equation for the vertical motion:
y = y
0
+ v
0
sin q t - 12 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.
Figure 1.1: Setup to shoot
horizontally off table