PASCO ME-6800 Projectile Launcher (Short Range) - Manual (Page 46)

P r o j e c t i l e L a u n c h e r T e a c h e r ’ s G u i d e
®
42 012-05043G
Questions
1. Momentum is conserved on both axes.
2. Kinetic energy is nearly conserved in the elastic collision. There is some loss of energy which indicates that
the collision is not perfectly elastics.
3. Momentum is conserved for the inelastic collision, but kinetic energy is not conserved.
4. The angle should be nearly 90°.
5. In the inelastic case, the angle will be less than in the elastic case. The exact angle will depend on the degree
of inelasticity, which will depend on the type and amount of tape used.
Exp. 7: Vary the Angle to Maximize the Height
Procedure
1. You should be able to measure the angle of maximum height to within ±2%.
2. Measure the distance to the front edge of the ball.
3. Measure the initial height to the center of the ball.
Analysis
1. The initial speed should be close to the initial speed determined by other methods. You may wish to determine
the initial speed by the method in experiment 1, and use that value in your calculations for the rest of the
experiment.
2. Measured value and calculated vale should agree to within 3%.
Questions
1. The ball will have passed its peak by the time it reaches the wall. To show this, take the derivative of y with
respect to x:
• substitute
• Substitute
y y
0
x

max
gx
2
2v
0
2  2
max
cos
-------------------------------- – tan + =
dy
dx
------ 
max
gx
2
v
0
2  2
max
cos
------------------------------- – tan =

max
v
0
2
gx
max
--------------
 
 
 
1 –
tan =
dy
dx
------
v
0
2
gx
max
--------------
gx
v
0
2
v
0
2
gx
max
--------------
 
 
 
1 –
tan
 
 
 
2
cos
-------------------------------------------------------- – =
a
b
---
 
  1 –
tan  
 
cos
b
a
2
b
2
+
--------------------- =