PASCO ME-6831 Ballistic Pendulum_Projectile Launcher - Manual (Page 57)

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M o d e l N o . M E - 6 8 3 0 T e a c h e r ’ s G u i d e
0 1 2 - 0 5 3 7 5 C 53
2. Vertical distances were measured from the ground up for this graph. The intercept is the height of the launcher
above the ground when done this way.
3. The slope (measuring from the ground) is -0.118 for this example. Measuring down from the initial height
will give the same value, except positive.) In either case, the slope is:
4. The slope calculated here gives us an initial speed of 6.44 m/s. This compares favorably with the speed calcu-
lated in experiments 1 and 2.
5. Results will vary with this method: the point of the activity is that individual measurements are not as accurate
as a large number of measurements and a curve fit.
Questions
1. Yes. This tells us that y is a function of x
2
.
2. A plot of y versus x would be parabolic instead of linear.
3. The projectile moves in a parabolic curve (if air resistance is neglected).
Exp. 5: Conservation of Energy
Analysis
1. Using the photogate method, the initial speed of the ball was found to be 4.93 m/s (for the short range
launcher at the medium range setting). The ball mass was 9.6 g, so the total kinetic energy was 0.117 J.
2. The ball reached an average height of 1.14 m (above the muzzle). The gravitational potential energy was
0.107 J.
3. The energy difference was 8.5% of the original kinetic energy.
4. NOTE: It seems unlikely that this much energy is lost due to air resistance, especially when you consider the
extraordinarily good results for labs 3 and 4. It is likely that the error here enters the calculation in the actual
measurements of initial velocity and maximum height.
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0
0.05
0.1
0.15
0.2
0.25
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Vertical Distance (m)
Horizontal Distance Squared (m^2)
f(x) = -1.181345E-1*x + 2.609457E-1
R^2 = 9.997926E-1
g
2v
0
2
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